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An evaluation of the system used by the British Columbia cancer registry to record data on cases of invasive… Husted, Janice Aileen 1982

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AN EVALUATION OF THE SYSTEM USED BY THE BRITISH COLUMBIA CANCER REGISTRY TO RECORD DATA ON CASES OF INVASIVE CERVICAL CANCER. by JANICE AILEEN HUSTED B.Sc.N., The U n i v e r s i t y o f B r i t i s h C o l u m b i a , 197^ A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department o f H e a l t h Care and E p i d e m i o l o g y ) We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA OCTOBER 1982 (F) J a n i c e A i l e e n H u s t e d , 1982 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department o f TLtitfu OWL The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date DE-6 (.3/81) Abstract This study evaluated the q u a l i t y of data recorded by the B r i t i s h Columbia (B.C.). Cancer Registry on cases of invasive c e r v i c a l cancer. This study did th i s by comparing the Registry's pathological diagnosis, age, marital status, residence, and date of death of a l l cases that had been registered as invasive c e r v i c a l cancer i n B.C. during 1977, 1978, and 1979 with a best estimate of the truth for these items of information, based on data c o l l e c t e d from B.C.'s cytology screening programme and from c l i n i c a l charts on f i l e at the Cancer Control Agency of B r i t i s h Columbia (CCA.B.C.) . This comparison showed that the Registry's data for these years over-estimated the true incidence of invasive c e r v i c a l cancer. One hundred and eighty-four (35%) of the Registry's 521 cases were not true cases of invasive c e r v i c a l cancer. Of these 184, 141 (77%) were cases of pre-invasive c e r v i c a l cancer; 26 (14%) did not f i t the c r i t e r i a of an incident case (a new case of invasive c e r v i c a l cancer diagnosed i n B.C. during 1977 to 1979); and 17 (9%) were cases of invasive cancer of another primary s i t e (e.g. bowel, endometrium). In addition to t h i s misreporting, 28 true cases of invasive c e r v i c a l cancer that had been diagnosed i n B.C. during 1977 to 1979 had not been reported to the Registry. Thus, there were errors of omission as well as commission. F i n a l l y , i t was found that the Registry only recorded 25 (29%) of the 85 f a t a l i t i e s that had occurred among the true cases of invasive c e r v i c a l cancer, and that the information on marital status was incorrect f o r 65% of cases, and, on residence for 30%. Further i n v e s t i g a t i o n revealed that a l l of these inaccuracies arose because of unsatisfactory r e g i s t r a t i o n procedures used by the Registry. In conclusion, the r e s u l t s of t h i s study indicate that there have been i i i shortcomings i n the data provided by the B.C. Cancer Registry for use i n monitoring the incidence of t h i s type of cancer over time; i n planning service f a c i l i t i e s for i t ; and evaluating the p r o v i n c i a l c e r v i c a l screening programme. - i v -TABLE OF CONTENTS Page Abstract i i Acknowledgement v i L i s t of Tables v i i L i s t of Figures i x Chapter 1: Introduction 1 Chapter 2: Background Information 3 2.1 Cancer R e g i s t r i e s 3 2.2 History of the B.C. Cancer Registry 5 2.3 History of the p r o v i n c i a l c e r v i c a l cancer screening programme and i t s l i n k with the B.C. Cancer Registry 8 Chapter 3: Materials and Method 11 Chapter 4: Results 13 4.1 P i l o t study 13 4.2 O v e r a l l r e s u l t s of comparison of diagnostic information 17 4.3 Reasons for the Registry's diagnostic errors 20 4.4 Comparison of information on fact of death 22 4.5 Comparison of information on age, m a r i t a l status, and residence 23 Chapter 5: Discussion 27 5.1 Quality of the Registry's recorded pathological diagnoses 27 5.2 Quality of the Registry's information on f a c t and date of death 32 5.3 Quality of the Registry's information on age, m a r i t a l status and residence 33 - v -References Appendix I: Appendix I I : Appendix I I I : Glossary The abstract used i n t h i s evaluation The method of c a l c u l a t i o n of the Registry's estimate and of the best estimate of the true age standardized incidence rates of invasive c e r v i c a l cancer i n B.C. Page 34 37 40 45 - v i -ACKNOWLEDGEMENT I would l i k e to express my gratitude to Professor Terence W. Anderson and to Richard P. Gallagher for th e i r supervision and assistance i n preparing t h i s t h e s i s . I also thank Dr. George Anderson for serving on my supervisory committee, and Dr. Mark Elwood f o r suggesting t h i s t o p i c . I am also very g r a t e f u l . t o the Cancer Control Agency of B r i t i s h Columbia (CCA.B.C.) . It provided many of the resources such as data, f i n a n c i a l support, and s t a f f cooperation and p a r t i c i p a t i o n that made i t possible to complete t h i s work su c c e s s f u l l y . I am p a r t i c u l a r l y indebted to Mary McBride and to Irene Lynnerup and her s t a f f f o r the many generous hours spent helping me with the data c o l l e c t i o n . F i n a l l y , my parents deserve thanks for th e i r u n f a l t e r i n g encouragement during the l a s t year. - v i i -L1ST OF TABLES Page o Table 4.1.1 P i l o t study of 57 cases, comparison of the Registry 14 diagnosis with a best estimate (see text) of the true diagnosis. C l a s s i f i e d by year and 'type of c e r v i c a l cancer. Table 4.1.2 P i l o t study, comparison of the Registry diagnosis 15 by type of c e r v i c a l cancer with a best estimate of the true diagnosis i n the 20 cases that were in c o r r e c t . Table 4.2.1 Comparison of the Registry diagnosis with a best 18 estimate of the true diagnosis. By year and type of c e r v i c a l cancer for the t o t a l (521) cases registered i n 1977 - 1979. Table 4.2.2 Comparison of the Registry diagnosis by type of 20 c e r v i c a l cancer with a best estimate of the true diagnosis i n the 184 cases that were i n c o r r e c t . Table 4.3.1 The Registry's misreported cases of invasive 22 c e r v i c a l cancers by type of error and by cause. Table 4.5.1 M a r i t a l status recorded by the Registry compared 25 with a best estimate of the true m a r i t a l status. Table 5.1.1 Comparison of the Registry's age-standardized 30 incidence rates with a best estimate of the true rates by year of diagnosis and by age group, using world population as standard population. - v i i i -Page Table 5.1.2 Comparison of the Registry's age-standardized 31 incidence rates with a best estimate of the true rates by year of diagnosis and by age group, using Canadian population as standard population. - i x -LIST OF FIGURES Page Figure 2.3.1 Natural h i s t o r y of invasive c e r v i c a l cancer. 9 Figure 4.1.1 The procedures leading to a f i n a l pathological 16 diagnosis of a c e r v i c a l abnormality. r- 1 -CHAPTER I: INTRODUCTION In developed countries cancer i s an important health problem. It i s one of the major causes of death and disease i n these populations. Numerous e f f o r t s are therefore being made to learn more about the nature and extent of cancer. I t i s hoped that the increased knowledge w i l l lead to improved methods of prevention, diagnosis and treatment of cancer and w i l l u l t i m a t e l y reduce i t s morbidity and mortal i t y . These e f f o r t s require accurate and r e l i a b l e information on the magnitude of the cancer problem; i t s d i s t r i b u t i o n i n various subgroups of the population (age, sex, residence, occupation and so f o r t h ) ; and the course and outcome of the i l l n e s s i n in d i v i d u a l s diagnosed with cancer. One of the major sources of such information i s a cancer r e g i s t r y . T y p i c a l l y , a cancer r e g i s t r y c o l l e c t s and stores, on an ongoing basis, a range of data r e l a t i n g to i n d i v i d u a l cases of cancer i n a we l l defined population ( h o s p i t a l , province, country). I t also analyzes these recorded data and produces s t a t i s t i c s on incidence* and mor t a l i t y from cancer by s i t e , sex, and age. These data can be used to look for upward or downward trends i n the incidence of a s p e c i f i c type of cancer. For example, i n B r i t i s h Columbia (B.C.) recorded data from the p r o v i n c i a l cancer r e g i s t r y was recently used to examine the trend i n incidence of invasive c e r v i c a l cancer (Gallagher, R. and Elwood, M. 1982). This-study showed that incidence of t h i s invasive cancer among women aged 15-44 since 1974 was increasing i n spite of widespread use of a p r o v i n c i a l c e r v i c a l cytology screening programme by young B.C. women. Similar reports have appeared elsewhere i n the l i t e r a t u r e (Yule 1978; Andrews et a l 1978; Antello et a l 1979; Berkowitz et a l 1979; Green 1979; * For d e f i n i t i o n of technical terms, see Appendix I. - 2 -P r e n d i v i l l e et a l 1980; Berkley et a l 1980). These reports prompt some queries: i s the increase due to improved diagnosis ( e s p e c i a l l y since the introduction of colposcopy)? improved n o t i f i c a t i o n ? a changing natural h i s t o r y of the disease with a t r u l y increased incidence? However, figures produced by the B.C. c e r v i c a l cytology screening programme d i f f e r e d i n that they showed a decreased incidence among women over 20 between 1955 and 1977 (Boyes et a l 1981). This downward trend has also been reported i n other areas (Walton Report 1976; McGregor et a l 1974). In an attempt to resolve t h i s discrepancy i n the reported incidence of invasive c e r v i c a l cancer i n B.C. i t was decided to evaluate the q u a l i t y of data recorded by the B.C. Cancer Registry on cases of invasive c e r v i c a l cancer. The main objective was to f i n d out i f the Registry was over-reporting the number of new cases of invasive c e r v i c a l cancer and therefore over-estimating the incidence of t h i s disease. A secondary objective was to assess the q u a l i t y of the follow-up (case f a t a l i t i e s ) and some of the demographic information (age, marital status, residence) recorded by the Registry on cases of invasive c e r v i c a l cancer. It was anticipated that t h i s study's findings would form the basis for remedial a c t i o n and improved functioning of the B.C. Registry. - 3 -CHAPTER 2: BACKGROUND This chapter i s divided into three sections. The f i r s t gives a short h i s t o r y of cancer r e g i s t r i e s . The second provides a h i s t o r y of the B.C. population based Cancer Registry. The t h i r d gives some background on the p r o v i n c i a l c e r v i c a l cancer screening programme and i t s l i n k with the B.C. Cancer Registry. 2.1 Cancer Regist r i e s 2.1.1 Aims The broad aim of a cancer r e g i s t r y i s to c o l l e c t , to store, and to report accurate and r e l i a b l e data that can be used i n cancer research and i n planning, administering and evaluating cancer programmes. T r a d i t i o n a l l y , most r e g i s t r i e s have accomplished t h i s by annually: (1) ascertaining the number of new cancers diagnosed i n a defined population; (2) c a l c u l a t i n g the incidence rates of these new cases of cancers; (3) determining the number of deaths from cancers i n a defined population; and (4) c a l c u l a t i n g m o r t a l i t y rates of these cancers. In the l a s t 10 to 20 years e f f o r t s have been made by many r e g i s t r i e s to increase the range of information compiled and generated by them i n order to achieve t h e i r broad aims more e f f e c t i v e l y . (Knowelden et a l 1970; Haenszel 1975; Barclay 1975; Grundmann 1975; Waterhouse 1980; Saxen 1980). These e f f o r t s were i n s t i g a t e d mainly by a c r i t i c i s m (Pedersen 1962; Staszewski 1975; Elwood and Gallagher 1980) that cancer r e g i s t r i e s , although consuming health care d o l l a r s , were generating information which was e i t h e r of l i m i t e d value- and/or already a v a i l a b l e from e x i s t i n g data banks (e.g. census and health insurance data). In some r e g i s t r i e s these e f f o r t s have resulted i n a d d i t i o n a l information being c o l l e c t e d and published, f o r example, data on the registered cases' treatment and follow-up and s u r v i v a l s t a t i s t i c s . _ 4 -2.1.2 Methods of Registration P r i o r to the 1960s these methods varied widely among the operating cancer r e g i s t r i e s i n the world. However, i n the l a t e 1960's, findings from research sponsored by the International Union Against Cancer (UICC) encouraged r e g i s t r i e s to develop standardized methods of operation. This research revealed that the data from various i n t e r n a t i o n a l r e g i s t r i e s could not be compared because of wide discrepancies i n t h e i r r e g i s t r a t i o n procedures. The primary source of diagnostic information, for example, was frequently not the same. Some r e g i s t r i e s used death c e r t i f i c a t e s to a s c e r t a i n new cases of cancer, while others used laboratory reports from pathology and/or cytology i n v e s t i g a t i o n s . The diagnosis of new cases of cancer obtained from laboratory reports was usually regarded as more r e l i a b l e than information from death c e r t i f i c a t e s because the l a t t e r was written at the terminal stage of the disease by attending physicians who sometimes did not have access to a l l medical information on cases (e.g. pathology reports, c l i n i c a l records). This was necessary to record accurately the cancer s i t e , type and behaviour and date of diagnosis. The r e l i a b i l i t y of recorded diagnoses therefore v a r i e d between r e g i s t r i e s and t h i s l i m i t e d the compara-b i l i t y of r e g i s t r i e s ' data, s p e c i f i c a l l y with respect to incidence of d i f f e r -ent types of cancer. Furthermore, the systems of cancer c l a s s i f i c a t i o n were often d i f f e r e n t as were the methods used to calculate the incidence and s u r v i v a l rates and the d e f i n i t i o n s of the v a r iables (personal and c l i n i c a l ) used to describe the cases. These differences further reduced comparability of r e g i s t r i e s ' data. Subsequently, i n d i v i d u a l s and agencies' ( i n t e r n a t i o n a l and national) published works discussing the materials and methods that were necessary to ensure that a r e g i s t r y ' s information was complete, accurate, and comparable. (Angelsio 1975; Barnes et a l 1975; Tuyns 1975; World Health Organization (WHO) 1976 a and b; Fujimoto et a l 1977; International Agency - 5 -for Research on Cancer (IARC) and International Association of Cancer Registr i e s (IACR) 1978; Saxen 1980; Waterhouse 1980). In Canada, the National Cancer I n s t i t u t e (1975) printed a manual, giving guidelines for planning and operating a r e g i s t r y that w i l l produce good data. 2.1.3 Evaluation The need for assessing the q u a l i t y of a r e g i s t r y ' s recorded information has recently been emphasized i n the l i t e r a t u r e . (WHO 1979; Elwood and Gallagher 1980). Past studies measuring the q u a l i t y of the data (Barclay 1975; IACR and IACR 1976) judged the performance l e v e l from the percent of h i s t o l o g i c a l confirmations and/or the percent of death n o t i f i c a t i o n s . A high r a t i o of pathology diagnoses to death r e g i s t r a t i o n s implied good data. Yet they recognized that inferences made about the grade of a r e g i s t r y ' s output should be based on an assessment which determines i f : one, the recorded p a t h o l o g i c a l diagnosis i s the most v a l i d ; two, the cancers are coded c o r r e c t l y i n view of s i t e , type and behaviour; and three, the r e g i s t r a t i o n i s complete. Moreover, they recommended that r e g i s t r i e s should s t a r t to do t h i s type of assessment i n order to monitor the q u a l i t y of data that are produced by them, thereby supporting t h i s evaluation of some of the B.C. Registry's recorded data on cases of invasive c e r v i c a l cancer. 2.2 History of the B.C. Cancer Registry This Registry has been i n operation since 1966. P r i o r to A p r i l 1980 i t was located i n the P r o v i n c i a l D i v i s i o n of V i t a l S t a t i s t i c s . At t h i s time i t was transferred to the D i v i s i o n of Data Services of the Cancer Control Agency of B.C. (CCA.B.C.) who assumed r e s p o n s i b i l i t y for i t s functioning. 2.2.1 Aims These are: (1) to a s c e r t a i n a l l cases of invasive and i n s i t u cancers, diagnosed i n B.C; - 6 -(2) to c a l c u l a t e incidence and prevalence rates, by age and sex, of invasive and i n s i t u cancers diagnosed i n B.C.; (3) to calculate s u r v i v a l rates for a l l cases of invasive and i n s i t u cancers diagnosed i n B.C.; and (4) to c o l l e c t demographic and follow-up data on cases f o r epidemiological and c l i n i c a l studies. In the past the Registry has p r i m a r i l y focussed on accomplishing the f i r s t 2 aims. However, with i t s r e l o c a t i o n to :the CCA.B.C. i n 1980 planning and organization i s being done by Registry personnel, i n order to achieve the other two aims. 2.2.2. Methods of Registration In B.C., cancer has been a n o t i f i a b l e disease since 1932. An actual reporting system was implemented i n 1935. From 1935 to 1966 t h i s system was based on d i r e c t n o t i f i c a t i o n from private physicians to the P r o v i n c i a l D i v i s i o n of V i t a l S t a t i s t i c s . In 1966, these n o t i f i c a t i o n s were redirected to the newly established B.C. Cancer Registry. However, reporting of new cases of cancers by physicians was never complete. In 1968, 30% of the cancers were s t i l l r egistered by a death c e r t i f i c a t e . In order to correct t h i s i t was decided by the Registry to request copies of a l l pathology reports that mentioned cancer from pathology la b o r a t o r i e s i n B.C. Thus, since 1969 the Registry's n o t i f y i n g system has been pr i m a r i l y based on pathology reports. A d d i t i o n a l reporting sources are death n o t i f i c a t i o n s , sent to the Registry from the P r o v i n c i a l D i v i s i o n of V i t a l S t a t i s t i c s ; private physicians; C C A . B . C cancer treatment centres, and h o s p i t a l medical records departments. The most recent figures published by the Registry stated that a pathology report was used to r e g i s t e r 82.8% of a l l cases of cancer, recorded as being diagnosed i n B.C. during 1978; a death n o t i f i c a t i o n was the sole source f o r 10.9% of cases; private physicians, cancer treatment centres or h o s p i t a l medical - 7 -records departments accounted for 6.3% of them. The f i r s t pathology report (or other type of report) received by the Registry f o r a new case of cancer i s the one that i s used to r e g i s t e r t h i s case. The cancer diagnosis and the i d e n t i f y i n g and demographic va r i a b l e s (name, address, age, sex, m a r i t a l status) from t h i s report are the data that are coded and stored on magnetic tape for each new case of cancer. I t should be mentioned that a l l the diagnoses are c l a s s i f i e d according to the Inter-n a t i o n a l C l a s s i f i c a t i o n of Diseases f o r Oncology (IDC-O). Follow-up of the registered cases involves recording data and cause of death. These data are c o l l e c t e d from the l i s t s of deaths i n B.C. that are compiled by the P r o v i n c i a l Department of V i t a l S t a t i s t i c s monthly and sent to the Registry. Registry s t a f f manually compare these death l i s t i n g s with the Registry's master l i s t i n order to a s c e r t a i n the deaths that occurred among cases and the dates and causes of these deaths. Other diagnostic information that i s generated on cases a f t e r t h e i r i n i t i a l r e g i s t r a t i o n and sent to the Registry i s not necess a r i l y entered into case computer f i l e s . In order to avoid the danger of underascertainment of new cases of invasive cancer, the Registry adopted a p o l i c y some years ago of accepting the most serious p a t h o l o g i c a l c l a s s i f i c a t i o n . Thus, i f the Registry's i n i t i a l diagnosis was of an invasive cancer, and subsequently a diagnosis of non invasive cancer was received the f i r s t diagnosis was l e f t unchanged. On the other hand, i f the i n i t i a l diagnosis was benign or pre-invasive cancer, and a subsequent one was invasive the Registry entry would be upgraded. Every year the Registry publishes a report containing data on the annual number of new cases of cancer diagnosed i n B.C. and of the deaths i n B.C. from cancers by age and sex. Annual incidence and mortality rates by age and sex are also produced. - 8 -2.2.3 Evaluation The Registry has not yet developed routine procedures f o r assessing the q u a l i t y of i t s recorded data. Some of the publications (CCA.B.C. 1980; McBride 1981) on the Registry have i n f e r r e d that diagnostic data on i t s cases are good by drawing attention to the high r a t i o of diagnoses made from path-ology reports to those made from death n o t i f i c a t i o n s . As outlined e a r l i e r , t h i s r a t i o i s widely used i n other parts of the world as an i n d i c a t o r of r e g i s t r y performance. 2.3 The History of the P r o v i n c i a l C e r v i c a l Cancer Screening Programme and  i t s l i n k with the B.C Cancer Registry In 1949 a cytology programme was introduced and subsequently a province wide programme was developed i n B.C. for a l l women over the age of 20 years i n the province. The objective of the programme was to determine i f cyt o l o g i c screening by Papanicolaou smears would r e s u l t i n a decrease i n both the incidence and mo r t a l i t y of invasive cancer of the cervix i n B.C This mass screening programme was j u s t i f i e d by the commonly accepted models of the natural h i s t o r y of c e r v i c a l cancer (Figure 2.3.1). This model shows that cancer of the cervix develops as a sequence of events, progressing with time. Normal c e r v i c a l c e l l s change to dy s p l a s t i c c e l l s ; dysplasia to i n s i t u cancer; and f i n a l l y , i n s i t u to invasive cancer. Current thinking i s that t h i s may take place over a period of approximately .10 to 20 years or more, although i n some cases the time i n t e r v a l i s considerably shorter. I t also implies that there i s a latent period within t h i s natural h i s t o r y during which c e r v i c a l cancer can be i d e n t i f i e d , diagnosed and treated p r i o r to : invasion, up to and including i n s i t u cancer. This model provided the ra t i o n a l e f o r the cytology screening programme. By means of a Papanicolaou smear (see Appendix I) within an apparently well female population, women can be i d e n t i f i e d who possibly have a pre-invasive - 9 -Figure 2.3.1 - Natural h i s t o r y of invasive c e r v i c a l cancer. See Appendix I for d e f i n i t i o n s of above precancerous and cancerous l e s i o n s . - 10 -cancer and further diagnostic procedures can confirm or refute t h i s p r o v i s i o n a l diagnosis. In B.C., the cytology report from a Papanicolaou smear i s sent to the woman's private physician. It gives information on the type of c e r v i c a l c e l l s detected (for example, normal or dy s p l a s t i c or c e l l s with cancer c h a r a c t e r i s t i c s ) and also makes a recommendation f o r further management, f o r example, a repeat smear i n 3 months or a diagnostic colposcopy. These two functions of the B.C. screening programme could help to reduce the incidence and mo r t a l i t y from invasive cancer of the cervix because they would prevent cases of preinvasive cancers progressing to invasive cancers. In order to evaluate the success of screening i n achieving t h i s objective, the p r o v i n c i a l cytology programme has reported annually (1962-1977) incidence and mortality rates of c l i n i c a l l y invasive squamous cancer of the cervix i n B.C. These figures show a consistent decrease i n both rates. (Boyes et a l 1981). The numerator data f o r these c a l c u l a t i o n s were c o l l e c t e d by requesting diagnostic and death information from the p r o v i n c i a l pathology laboratories and/or the CCA.B.C. treatment centres and/or the Cancer Registry. The data that were received from these sources were assessed f o r accuracy (by checking the cases' c l i n i c a l chart or contacting t h e i r private physician or reviewing the pathology s l i d e s ) before they were recorded by the screening programme. This procedure l e d to a suspicion that the r e g i s t r y was over-reporting the number of new cases of invasive c e r v i c a l cancer diagnosed i n B.C. - 11 -CHAPTER 3: MATERIALS AND METHOD The data for t h i s evaluation came from three sources. The f i r s t source was the B.C. Cancer Registry which c o l l e c t s information on a range of variables f o r a l l cases of invasive, borderline invasive, and i n s i t u cancers, diagnosed i n B r i t i s h Columbia. The second was the p r o v i n c i a l c e r v i c a l cytology screening programme which compiles c l i n i c a l , c y t o l o g i c a l and patho-l o g i c a l information on women i n B.C. who have had a Pap smear. The t h i r d source was the c l i n i c a l chart of the cancer treatment centres which contains personal, diagnostic and c l i n i c a l information on cases of cancers that are refe r r e d to these centres for diagnosis and/or treatment. The evaluation compared the Registry's pathological diagnosis, age, ma r i t a l status, residence and date of death of a l l the cases that i t had recorded as being diagnosed with invasive cancer of the cervix i n 1977, 1978, and 1979 with a "best estimate" of the " t r u t h " f or these 5 v a r i a b l e s . This was based on data c o l l e c t e d from the cytology screening programme and the c l i n i c a l chart. Only three years of the Registry's t o t a l output were assessed because of the lack of time to v a l i d a t e a l l the recorded data available since 1969. Also, looking at these s p e c i f i c years would help the cytology screening programme by updating the incidence s t a t i s t i c s on c l i n i c a l l y invasive squamous c e l l cancer of the cervix. The Registry's research o f f i c e r produced a master l i s t that gave the name, pathology diagnosis, age, m a r i t a l status, residence and date of death for every case of invasive c e r v i c a l cancer diagnosed i n 1977, 1978 and 1979. In addition, other information such as: the date of diagnosis, source of report, date of report, and method of diagnosis was included on t h i s master l i s t because i t was f e l t that these v a r i a b l e s might help to i d e n t i f y the reasons for any m i s c l a s s i f i c a t i o n s of pathological diagnoses by the Registry. - 12 -The cytology programme keeps a card f i l e f o r every case of cancer of the cervix. This f i l e contains a l l the pathology reports generated during the diagnosis and treatment of the case. It.was therefore not necessary to contact h o s p i t a l s and/or p r a c t i t i o n e r s i n order to locate the pathology reports that were used to confirm or to refute the Registry's pathological diagnosis. Another source of information was the c l i n i c a l chart from the Vancouver or V i c t o r i a treatment centres. This was used to gather a d d i t i o n a l demographic data, the date of death and the autopsy report because the records i n the cytology department often did not have complete information on these var i a b l e s . Each chart had an admission sheet giving the age, marital status and residence and, when applicable, i t also contained the death c e r t i f i c a t e (and thus the date of death) and the autopsy report, i f an autopsy was performed. An abstract form (Appendix II) was developed to code the data received from the Registry and other sources of data for t h i s evaluation. An analysis was then c a r r i e d out, comparing the Registry's information on age, residence, m a r i t a l status, date of death and pathological diagnosis with that from the other sources. Then, a review of the pathology reports from which the misreported cases were registered was made i n order to learn the causes of the Registry's misreporting. v. CHAPTER 4: RESULTS Sections 4.1 to 4.3 give the r e s u l t s of the comparison of the Registry's pathological diagnosis with the best estimate of the true pathological diagnosis based on the cytology records and c l i n i c a l charts. Section 4.4 and 4.5 give the r e s u l t s of the comparison of the Registry' information on date of death, age, ma r i t a l status and residence with the best estimate from other sources. 4.1 The P i l o t Study A p i l o t study was c a r r i e d out on a sample of 11% of Registry cases to ensure that i t was possible to e s t a b l i s h a v a l i d diagnosis from the case f i l e s i n the cytology department and that the pathology codes that were used i n th i s evaluation's abstract form adequately represented a l l the types of c e r v i c a l cancer l i k e l y to be encountered. The f i r s t f i n d i n g (Table 4.1.1) was that 20 (35%) of the Registry's 57 diagnoses were inaccurate. Table 4.1.2 shoxvs that i n 15 cases the true diagnosis was pre-invasive cancer (carcinoma i n s i t u ) ; i n 3 cases the primary s i t e of the invasive cancer was not the cervix; and the other 2 cases did not meet the Registry's c r i t e r i a f o r an incident case (a new case of invasive c e r v i c a l cancer diagnosed i n B.C. during 1977 to 1979). The second f i n d i n g was that more than one pathology report was often needed to e s t a b l i s h a v a l i d pathological diagnosis of cancer of the cervix. As i l l u s t r a t e d i n the diagram (Figure 4.4.1) there are a number of places where the f i n a l diagnosis may be changed from the one based on the f i r s t biopsy. For example, the diagnosis from a colposcopy may a l t e r following a cone biopsy and/or hysterectomy. This was an important f i n d i n g because i t explained why 18 (90%) of the misreported cases discovered i n the p i l o t test had occurred. The Registry's Table 4.1.1 - P i l o t study of 57 cases, comparison of the Registry diagnosis with a best estimate (see text) of the true diagnosis. C l a s s i f i e d by year and type of c e r v i c a l cancer. INVASIVE CERVICAL CANCERS (ICD-0 CLASSIFICATION) C l i n i c a l l y invasive squamous c e l l carcinoma 8070/3 Micro or occult invasive squamous c e l l carcinoma 8070/4 Uncertain whether invasive squamous c e l l carcinoma 8070/8 C l i n i c a l l y invasive e p i t h e l i a l carcinoma 8010/3 Uncertain whether invasive e p i t h e l i a l carcinoma 8010/8 C l i n i c a l l y invasive undifferentiated e p i t h e l i a l carcinoma 8020/3 Uncertain whether invasive undifferentiated e p i t h e l i a l carcinoma 8020/8 C l i n i c a l l y invasive adenocarcinoma 8140/3 Uncertain whether invasive • adenocarcinoma 8140/8 C l i n i c a l l y invasive p a p i l l a r y adenoma 8260/3 C l i n i c a l l y invasive c l e a r c e l l adenocarcinoma 8310/3 C l i n i c a l l y invasive adenosquamous carcinoma 8560/3 TOTAL 1977 Registry Best Estimate Of Truth 1978 1979 TOTAL Registry Best Estimate Registry Best Estimate Registry Best Estimate Of Truth Of Truth 12 3 14 2 34 8 3 2 Of Truth 19 12 19 15 19 13 19 57 37 ^ - 15 -Table 4.1.2 - P i l o t study, comparison of the Registry diagnosis by type of c e r v i c a l cancer with a best estimate of the true diagnosis i n the 20 cases that were i n c o r r e c t . INVASIVE CERVICAL CANCERS (ICD-0 CLASSIFICATION) Uncertain whether und i f f e r e n t i a t e d e p i t h e l i a l carcinoma C l i n i c a l l y invasive squamous carcinoma Uncertain whether invasive squamous carcinoma C l i n i c a l l y invasive adenocarcinoma Uncertain whether invasive adenocarcinoma C l i n i c a l l y invasive p a p i l l a r y adenoma 8020/8 8070/3 8070/8 8140/3 8140/8 8260/3 To t a l u cu o s~ CJ CSI r-i O CU O CJ 00 cn 3 3 0 -u 1 co 3 ' cr c C/D -ri CO \ e o o C r-1 •H 00 O w U c8 O O C 0) < cu u ca m co o •H CO cu O T3 C -H M 01 ca w •H 3 P O X •rl > U co cu CJ U 4J ca o a a •ri J-J CO PM -H C O •ri U ca w CO •rl M cu r l CU •U ca o •rl rH ft 3 P ca 4-1 o H 1 1 9 1 1 11 3 3 1 2 3 1 1 1 1 13 2 1 3 1 20 - 16 -Figure 4.1.1 - The recommended procedures of CCA.B.C. that lead to f i n a l pathological diagnosis of a c e r v i c a l abnormality. This figure i s a modified version of the one shown i n a recent paper by Benedet, J. and Anderson, G. (1981). women with symptoms of c e r v i c a l cancer normal or abnormal Pap smear no Pap smear colposcopy-directed biopsy punch biopsy d i l a t a t i o n and curettage wedge biopsy' women with no symptoms of c e r v i c a l cancer abnormal "screening" Pap smear(s ) colposcopy-directed biopsy punch biopsy ( d i l a t a t i o n and curettage and wedge biopsy are uncommon) further diagnostic procedure i f + for cancer of cervix or severe dysplasia cone biopsy and/or CCA.B.C. re-evaluation procedure treatment s u r g i c a l treatment cone biopsy and/or hysterectomy other treatment cryotherapy or l a s e r therapy (no further pathological diagnosis) r a d i a t i o n (no further pathological diagnosis) autopsy (infrequently done i n B.C.) hysterectomy or hysterectomy and r a d i a t i o n C • C • A. • B • C • re-evaluation procedure - 17 -diagnosis of invasive cancer for these 18 cases was based on the diagnosis on the f i r s t pathology report that the Registry received. However, the most v a l i d diagnosis for each of these cases was made from subsequent specimens of tissue and/or from a pathologist's of the CCA.B.C. re-evaluation of the material used to make the f i r s t p athological diagnosis. This a d d i t i o n a l information was not entered into the Registry for 2 reasons. . The f i r s t one was the Registry's routine procedure of recording a l l cases of c e r v i c a l cancer as invasive unless the f i r s t pathology report s p e c i f i c a l l y stated carcinoma i n s i t u or dysplasia. This i n i t i a l diagnosis of invasive cancer was never down-graded to non-invasive to r e f l e c t l a t e r information. This led to the i n c l u s i o n of 15 cases of carcinoma i n s i t u . The second reason was that the Registry did not receive the information from the CCA.B.C. re-evaluation procedure which changed the primary s i t e diagnosis of 3 cases. 4.2 The O v e r a l l Results Study of a l l cases for the years 1977-1979 gave s i m i l a r r e s u l t s to the p i l o t study: 326 (63%) of the Registry's 521 recorded cases were confirmed p a t h o l o g i c a l l y as invasive cancer of the cervix (Table 4.2.1); 184 (35%) were reported i n c o r r e c t l y (Table 4.2.2); and for the remaining 11 (2%) of the 521 cases i t was not possible to confirm or to refute the recorded diagnoses. Of the 184, 141 (77%) were a c t u a l l y pre-invasive cases, e i t h e r i n s i t u or with a l e s s e r degree of dysplasia; 17 (9%) were invasive cancer of other s i t e s ; and 26 (14%) did not f i t the c r i t e r i a (outlined e a r l i e r ) for an incident case. Ten of the 26 cases had an i n c o r r e c t incident year, and i n a l l cases the recorded incident year was at l e a s t 5 years i n error with diagnosis having occurred i n the 1960s or the e a r l y 1970s. F i n a l l y , i t was found when reviewing the cytology case f i l e s and c l i n i c a l charts that 28 cases of c l i n i c a l l y invasive squamous c e l l cancer of the cervix, diagnosed i n 1977 to 1979 had not been included on the Registry's master l i s t Table 4.2.1 - Comparison of the Registry diagnosis with a best estimate of the true diagnosis. By year and type of c e r v i c a l cancer for the t o t a l (521) cases registered i n 1977-1979. INVASIVE CERVICAL CANCERS (CATEGORIZED BY ICD-0 SYSTEM) Unc l a s s i f i e d invasive neoplasm 8000/3 C l i n i c a l l y invasive e p i t h e l i a l carcinoma 8010/3 Micro or occult invasive e p i t h e l i a l carcinoma 8010/4 Uncertain whether invasive e p i t h e l i a l carcinoma 8010/8 C l i n i c a l l y invasive undifferentiated e p i t h e l i a l carcinoma 8020/3 Uncertain whether invasive undifferentiated e p i t h e l i a l carcinoma 8020/8 C l i n i c a l l y invasive anaplastic e p i t h e l i a l carcinoma 8021/3 C l i n i c a l l y invasive p a p i l l a r y carcinoma 8050/3 C l i n i c a l l y invasive verrucous carcinoma 8051/3 Borderline malignancy squamous c e l l carcinoma 8070/1 C l i n i c a l l y invasive squamous c e l l carcinoma 8070/3 Micro or occult invasive squamous c e l l carcinoma 8070/4 Uncertain whether invasive squamous c e l l carcinoma 8070/8 C l i n i c a l l y invasive squamous c e l l ( k e r a t i n i z i n g type carcinoma) 8071/3 1977 Registry Best Estimate Of Truth 1978 1979 TOTAL Registry Best Estimate Registry Best Estimate Registry Best Estimate Of Truth Of Truth Of Truth 1 10 5 112 18 62 29 101 25 48 42 2 1 1 3 95 29 20 60 30 7 27 13 2 2 2 1 3 308 72 20 0 0 0 0 0 170 101 0 1 continued Table 4.2.1 - continued INVASIVE CERVICAL CANCERS (CATEGORIZED BY ICD-0 SYSTEM) C l i n i c a l l y invasive squamous c e l l (large c e l l ) carcinoma C l i n i c a l l y invasive basosquamous carcinoma C l i n i c a l l y invasive adenocarcinoma Micro or occult invasive adenocarcinoma Uncertain whether invasive adenocarcinoma C l i n i c a l l y invasive p a p i l l a r y adenoma C l i n i c a l l y invasive clear c e l l adenocarcinoma C l i n i c a l l y invasive mucinous adenocarcinoma C l i n i c a l l y invasive adenosquamous carcinoma Micro or occult invasive adenosquamous carcinoma C l i n i c a l l y invasive leiomyosarcoma C l i n i c a l l y invasive rhabdomyosarcoma C l i n i c a l l y invasive embryonal rhabdomyosarcoma Endometrial stromal sarcoma 1977 Registry Best Estimate Of Truth 8072/3 -8094/3 1 1 8140/3 19 8 8140/4 - 3 8140/8 8260/3 8310/3 1 1 8480/3 8560/3 4 7 8560/4 8890/3 1 1 8900/3 1 1 8910/3 1 1 8930/3 TOTAL 174 116 1978 Registry Best Estimate Of Truth 1979 Registry Best Estimate Of Truth TOTAL Registry Best Estimate Of Truth 2 1 2 1 1 1 9 7 5 1 33 16 " - 1 0 4 I - 1 0 1 - 3 1 4 1 1 1 - 2 2 1 - - - 1 0 5 7 2 3 11 17 1 3 1 3 I I 2 2 - 1 1 - - 1 1 1 - - 1 0 161 105 186 105 521 326 Table 4.2.2 - Comparison of the Registry diagnosis by type of cervical cancer with a best estimate of the true diagnosis in the 184 cases that were incorrect. INVASIVE CERVICAL CANCERS (CATEGORIZED BY ICD-0 SYSTEM) Unclassified invasive neoplasm 8000/3 Clinically invasive epithelial carcinoma 8010/3 I Micro or occult invasive epithelial carcinoma 8010/4 O Uncertain whether invasive epithelial carcinoma 8010/8 ^ Uncertain whether invasive undifferentiated epithelial carcinoma 8020/8 Clinically invasive papillary carcinoma 8050/3 Borderline malignancy squamous ce l l carcinoma 8070/1 Clinically invasive squamous c e l l carcinoma 8070/3 Micro or occult invasive squamous c e l l carcinoma 8070/4 Uncertain whether invasive squamous ce l l carcinoma 8070/8 Clinically invasive squamous c e l l (large cell) carcinoma 8072/3 Clinically invasive adenocarcinoma 8140/3 Uncertain whether invasive adenocarcinoma 8140/8 Clinically invasive papillary adenoma 8260/3 Clinically invasive mucinous adenocarcinoma 8480/3 Clinically Invasive adenosquamous carcinoma 8560/3 Endometrial stromal sarcoma 8930/3 TOTAL 01 C <U 10 « O >, -rt •rt X -rt 01 W *rt 0) U u O > * J ra o c >> ri HJ rl 0) 00 M 01 CJ 4J M to 10 CJ -rl 10 rl *rt rH B H iH O ~0 10 •rt U CL 00 <J U rl O 3 0) C O PL: C Q Ll M O E-H 3 2 1 6 2 2 3 1 1 2 5 16 3 3 1 1 2 1 1 1 1 2 2 1 3 6 86 1 5 3 7 3 111 7 1 8 15 15 1 1 4 2 1 1 8 1 1 2 2 1 1 1 2 3 1 1 10 10 a B CD o o T J a c •H tO •rt •rt CO •rt o CJ 4J 3 CN to o u Li •*-* 10 ~~— 10 ,—, 10 o •H o iH o o CM CH o CM to rH O. to ~ - CU 01 O to rrt O rH O B O to o *o G to 00 rH 00 rH O ~I 3 nj •rt •rt *—' 01 *—- 01 o C -1 o IT) s £ o O CO •rt CO OO 10 H r ? ~ 10 o 10 —' O ^ CO s 0) 10 •rt to rl 3 •H o .c •H 3 10 3 3 10 3 cr 3 CO • i*H i-t ^ o to O 4-1 U 4J to 4J O O •rt o •rt rH O i rH s •rt O IH o T * C • U U •rt ""1 53 CL Si to C to c (0 W) CQ cd rl L» CO CL O 3 to 3 01 0) (0 O CL to oo tr cr c •o c c •H 4-t c_> c 10 PM ^ CO •o CO •rt «< -rt <; •H Q o 2 1 10 119 6 3 6 17 10 10 184 - 2 1 -of a l l new cases of invasive c e r v i c a l cancer diagnosed i n B.C. between 1977 to 1979. Thus, there were errors of omission as we l l as commission. 4.3 The Reasons for Registry's Errors The factors responsible for the 184 cases being reported i n c o r r e c t l y are presented i n Table 4.3.1. It can be seen that incomplete pathology information caused 130 (71%) of the Registry's e r r o r s . The 113 cases showing pre-invasive behaviour were diagnosed as such subsequent to the i n i t i a l biopsy e i t h e r by a cone biopsy, a hysterectomy, a d i l a t a t i o n and curettage, or the CCA.B.C. re-evaluation procedure. But as outlined i n Section 4.1, the Registry's diagnosis of invasive cancer for these 113 cases was recorded from the f i r s t pathology report and remained unchanged. I t originated from a co l p o s c o p i c a l l y directed biopsy (see Appendix I) i n 96% of cases. The diagnosis from t h i s report was usually "cancer of the ce r v i x " with or without the a d d i t i o n a l phrase "with an i n s u f f i c i e n t amount of tissue to assess f o r invasion." The Registry's usual procedure was to record such a case as an invasive cancer of the cervix :and t h i s diagnosis was not subsequently revised to r e f l e c t the diagnostic changes made by the further investigations before or during treatment. The 17 invasive cancers of the bowel or the endometrium or the ovaries were recorded as invasive cancers of the cervix and l e f t unchanged because the Registry did not receive information on the most v a l i d diagnosis f o r these cases. This information originated e i t h e r from the CCA.B.C. re-evaluation of i n i t i a l t i ssue specimen or an autopsy report. Coding errors that were made while r e g i s t e r i n g a new case accounted f o r 31 (17%) of the Registry's i n c o r r e c t l y reported diagnoses. The commonest mistake was the coding of a carcinoma i n s i t u as an invasive rather than a pre-invasive cancer. The poor q u a l i t y of the information submitted to the Registry caused - 22 -Table 4.3.1 - The Registry's misreported cases of invasive c e r v i c a l cancers by type of err o r and by cause. Causal Factors Type of Error Pre-invasive lesions Incorrect primary s i t e Incorrect incident year Out of Province diagnosis Duplicate r e g i s t r a -t i o n TOTAL Incomplete pathology information on the case 113 17 130 Coding errors during r e g i s t r a t i o n of the case 28 31 Inaccurate information on the case sent to the Registry 14 Registration of the case by a death n o t i f i c a t i o n instead of a pathology report TOTAL 141 17 10 10 184 - 23 -the remaining 12% of the e r r o r s . Fourteen (7%) occurred because the case's name or the place of diagnosis on the pathology report that was used to reg-i s t e r the case was inaccurate, r e s u l t i n g i n e i t h e r duplicate r e g i s t r a t i o n s or the r e g i s t r a t i o n of an out of province diagnosis. A further 9 (5%) arose because a death n o t i f i c a t i o n instead of a pathology report was used to r e g i s t e r the case. On i n v e s t i g a t i o n , the 9 cases were not new cases of invasive c e r v i c a l cancer. Each case had been diagnosed several years p r i o r to death and was not registered at that time because the Registry had not received pathology reports for these cases. The factor responsible for 28 cases of invasive squamous c e l l cancer of the cervix not being recorded by the Registry was incomplete n o t i f i c a t i o n of a l l p o s i t i v e cases. Thus, the pathology reports of these cases had not been sent by the CCA.B.C. cancer treatment centres or the pathology laboratories to the Registry. 4.4 Comparison of Information on Date of Death, or Fact of Death As of May, 1981 the Registry's data indicate that 42 deaths had occurred among the 521 cases that were registered as being diagnosed with invasive c e r v i c a l cancer i n 1977, 1978 and 1979, while t h i s evaluation uncovered 104 deaths by checking c l i n i c a l charts. Moreover, when the Registry's misreported cases were excluded, the Registry's data indicated that only 25 deaths had occurred among the 326 cases of invasive c e r v i c a l cancer, while t h i s evaluation uncovered 85 deaths or over 3 times as many as the Registry's. This indicated that the Registry under-reported i t s case f a t a l i t i e s to a s u b s t a n t i a l degree. Three reasons for this were discovered by reviewing the follow-up procedures previously described i n Section 2.2 and by communicating with Registry s t a f f . Three deaths had taken place outside B.C. and would have been excluded from the monthly l i s t s of deaths i n B.C. that had been compiled by the p r o v i n c i a l Department of V i t a l S t a t i s t i c s and which had provided the - 24 -Registry with i t s information on case f a t a l i t i e s . In addition, i t was often 2 to 6 months before a death was n o t i f i e d , v i a these l i s t s , to the Registry. Thus, i t i s clear that as of May 1981 (the time when the Registry's information was generated f o r th i s evaluation), some of the 23 deaths which occurred among the cases i n 1980 and 1981 would not yet have been reported to the Registry. F i n a l l y , the Registry was approximately one year behind i n i t s manual follow-up procedure. 4.5 Comparison of Information on M a r i t a l Status, Age and Residence As discussed i n Chapter 3, part of the intent of t h i s i n v e s t i g a t i o n was to compare the data on these three variables f o r a l l cases recorded by the Registry as being diagnosed with invasive c e r v i c a l cancer i n 1977, 1978 and 1979 with a "best estimate" of the " t r u t h " obtained from the cases' c l i n i c a l chart. In f a c t , i t was only possible to examine 189 (58%) of the Registry's 326 p a t h o l o g i c a l l y confirmed cases. The other 137 (42%) were not treated at the V i c t o r i a or Vancouver cancer c l i n i c s so that c l i n i c a l charts were not ava i l a b l e from which to c o l l e c t data on age, ma r i t a l status, and residence, or they were treated at these two cancer c l i n i c s but t h e i r charts were for some reason not av a i l a b l e f o r review. As indicated i n Table 4.5.1, f o r 94 (49%) of the 190 cases, marital status was not given on the pathology reports used to r e g i s t e r the case. For the remaining 96 (51%) of the cases, 30 (31%) were coded as married instead of widowed or divorced or separated, because the Registry's source of i n f o r -mation for t h i s v a r i a b l e , a pathology report, only discriminated between sing l e (Miss) or married (Mrs.). For 185 (97%) of the 190 cases, the age recorded by the Registry appeared "true" to within one year. T o t a l agreement was not to be expected because the Registry's data on age were recorded at the time of the f i r s t pathology report and c l i n i c a l records showed age at the time of the,case's admission to - 25 -Table 4.5.1 - M a r i t a l status recorded by the Registry compared with a best estimate of the true marital status. Registry Best estimate of the true m a r i t a l status Code Absolute (N) Relative (%) Absolute (N) Relative 1. Single 5 2.6 12 6.3 2. Married 91 48.0 116 61.0 3. Widowed 0 0 39 20.5 4. Divorced 0 0 16 8.5 5. Separated 0 0 7 3.7 6. Unknown 94 49.4 0 0 190 100.00 190 100.0 the cancer c l i n i c . For 57 (30%) of the 190 cases, the place of residence recorded by the Registry was i n c o r r e c t . These errors occurred because the Registry recorded the residence of a case as the c i t y where the f i r s t pathology report originated. Therefore, these 57 cases who a l l l i v e d i n outlying areas of northern B.C. or northern Vancouver Island but were ref e r r e d to Vancouver or V i c t o r i a or Kamloops f o r the i n i t i a l diagnostic procedure were coded as residents of these c i t i e s instead of t h e i r home towns. CHAPTER 5: DISCUSSION AND CONCLUSION This chapter i s divided into three sections: (1) the q u a l i t y of the Registry's pathological diagnoses; (2) the q u a l i t y of the Registry's i n f o r -mation on the factor date of death; and (3) the q u a l i t y of the Registry's information on age, marital status and residence. 5.1 The Quality of the Registry's Recorded Pathological Diagnoses 5.1.1 The findings revealed that the Registry's reported number (521) of new cases of invasive c e r v i c a l cancer, diagnosed i n B.C. during the years of 1977, 1978 and 1979 was about 50% too high. One hundred and eighty-four (35%) of the 521 cases were not true cases of invasive c e r v i c a l cancer. I t was found that these errors arose because of problems with the methods of r e g i s t r a t i o n . The major problem was the Registry's lack of a procedure to revise the f i r s t diagnosis recorded by the Registry so as to r e f l e c t the diagnostic changes occurring a f t e r i n i t i a l r e g i s t r a t i o n . This problem i s not unique to the B.C. Registry, as i t has been documented i n the l i t e r a t u r e f or other r e g i s t r i e s (Ravinhar, B. et a l 1975; WHO, 1976a; IARC and IACR, 1978). These works drew attention to the need of a cancer r e g i s t r y to e s t a b l i s h procedures that c o l l e c t and record a l l the pathological information generated during the routine diagnosis and treatment of registered cases. This was seen as the best means to ensure that a r e g i s t r y had recorded the best f i n a l diagnosis for each case. 1 The current i n v e s t i g a t i o n also indicated that the widespread use of colposcopy-directed biopsy i n B.C. has increased the Registry's need for such a r e v i s i n g procedure. Since 1974 (Benedet, J.L. et al) i t has usually been the f i r s t diagnostic procedure, performed on women with an abnormal pap smear(s) but without signs or symptoms of c e r v i c a l cancer, i n order to detect cases of pre-invasive c e r v i c a l cancer. The pathology report from the colposcopy biopsy i s therefore the f i r s t report received by the Registry for these cases and i t s diagnosis i s the one that i s recorded by the Registry. However, frequently the tissue fragments from t h i s type of biopsy are too small to allow a pathologist to diagnose the c e r v i c a l cancer as invasive or pre-invasive ( i n s i t u ) . Another biopsy (e.g. cone) or hysterectomy i s necessary to determine t h i s . In the present i n v e s t i g a t i o n , 108 (96%) of the 113 cases recorded by the Registry as invasive c e r v i c a l cancer but found to be pre-invasive cases of cancer were registered from a pathology report that was generated from a colposcopy biopsy. For a l l these cases, a subsequent cone biopsy or s u r g i c a l specimen revealed that the cancer was pre-invasive but t h i s diagnostic f i n d i n g was not entered i n t o the Registry's m a s t e r f i l e because of i t s p o l i c y not to downgrade a diagnosis of invasive c e r v i c a l cancer made at i n i t i a l r e g i s t r a -t i o n (as outlined e a r l i e r i n Section 2.2.2). I t i s also evident that i f the Registry decides to implement a r e v i s i n g procedure i t should be done i n conjunction with e f f o r t s to improve the n o t i f i c a t i o n rate of cases of c e r v i c a l cancer, since i n 50% of the pre-invasive cases that were recorded i n c o r r e c t l y as invasive the pathology reports from the treatment or in v e s t i g a t i o n s following the i n i t i a l biopsy were not sent to the Registry. A s i m i l a r i n t e r p r e t a t i o n of the e f f e c t of colposcopy on the Registry's inaccurate reporting of invasive c e r v i c a l cancer was given by Boyes et a l (1981). They stated that the observed r i s e i n the Registry's recorded number of new cases of invasive c e r v i c a l cancer i n the mid '70's was an a r t e f a c t because i t coincided with the introduction of the colposcopy directed biopsy on a large scale i n B.C. They suggested that t h i s reported increase was caused by the i n c l u s i o n of cases of pre-invasive cancer and they supported t h i s argument with findings from a review of a l l the cases reported by the - 29 -Registry as being diagnosed with invasive c e r v i c a l cancer i n 1975. They also j u s t i f i e d this explanation by i n d i c a t i n g that t h i s type of misreporting by the Registry would not have occurred p r i o r to the introduction of the colposcopy because the cone biopsy was the i n i t i a l diagnostic procedure at that time. This type of biopsy usually produces s u f f i c i e n t tissue to allow a pathologist to accurately diagnose whether the cancer i s invasive or i n s i t u . The other problems that caused the Registry to misreport cases were coding errors during the r e g i s t r a t i o n of the case and poor information received by the Registry. These same problems have been i d e n t i f i e d i n other cancer r e g i s t r i e s (WHO, 1979; IARC and IARC, 1978; Barclay, 1975; Saxen, 1980). The commonest conclusion was that accuracy of recorded data can be improved by i n s t i t u t i n g ongoing q u a l i t y control procedures that check the r e l i a b i l i t y of the information received and the consistency of coding practices. An important i m p l i c a t i o n of the Registry's. inaccurate reporting of the number of new cases of invasive' c e r v i c a l cancer i n 1977, 1978, and 1979 was that the recorded numbers, when used to calculate age standardized incidence rates, i n f l a t e d these rates (Table 5.1.1 and Table 5.1.2). This was pa r t i e s u l a r l y true for the age.group between 15-44. Overestimation i n t h i s group was high because of the i n c l u s i o n of cases of pre-invasive c e r v i c a l cancer. This type of erro r probably occurred predominantly i n t h i s age group and not i n the others for several reasons such as: (1) the absolute frequency of pre-invasive lesions was maybe higher i n younger women; (2) the r e l a t i v e frequency, that i s , the proportion of a l l l e s i o n s that were pre-invasive was higher i n younger women; (3) younger women were more l i k e l y to have had a Papanicolaou smear, increasing the l i k e l i h o o d of detecting pre-invasive l e s i o n s ; and (4) younger women with abnormal Papanicolaou smears were more l i k e l y to have had a colposcopy rather than a cone biopsy or hysterectomy or d i l a t a t i o n and curettage. - 30 -Table 5.1.1 - Comparison of the Registry's age-standardized incidence rates with a best estimate of the true rates by year of diagnosis and by 5 year age groups, using world population as standard population. See Appendix III for the method of c a l c u l a t i o n of these age standardized rates. AGE GROUP 1977 1978 1979 15 - 44 Registry's rates 14.11 14.95 16.96 Best estimate of true rates 8.68 8.60 8.95 45 - 64 Registry's rates 24.77 16.97 20.44 Best estimate of true rates 19.98 13.94 16.87 65+ Registry's rates 24.98 21.37 21.26 Best estimate of true rates 18.48 19.52 13.48 - 31 -Table 5.1.2 - Comparison of the Registry's age-standardized incidence rates with a best estimate of the true rates by year of diagnosis and by 5 year age groups, using Canadian population as standard population. See Appendix III for the method of c a l c u l a t i o n of these age standardized rates. AGE GROUP 19.77 1978 1979 15 - 44 45 - 64 65+ Registry's rates 13.57 14.43 16.36 Best estimate of true rates 8.07 8.30 • 8.39 Registry's rates 24.64 17.03 20.47 Best estimate of true rates 19.99 13.99 17.08 Registry's rates 23.00 21.50 21.54 Best estimate of true rates 16.48 19.35 13.49 - 32 -It i s c l e a r that the Registry's rates f o r these years should be used with caution by persons who are evaluating the e f f e c t of B.C.'s cytology screening programme on incidence trends or planning the number and type of f a c i l i t i e s that are needed to treat cases of invasive c e r v i c a l cancer. Another i m p l i c a t i o n of the present study i s that the Registry may have over-reported the number of new cases of other types of cancers. This would have occurred most frequently i n the case of cancers whose i n i t i a l diagnosis generated from the f i r s t biopsy sometimes changes because of a subsequent pathological diagnosis established during the course of the disease (e.g. cancer of the colon). The Registry probably has not recorded the case's f i n a l diagnosis. 5.1.2 I t was also found that the Registry's reported number (521) of new cases of invasive c e r v i c a l cancer f o r the three years f a i l e d to include 28 "true" cases. I t i s possible that the true number of missed cases was higher than 28, since by the very nature of the problem i t i s impossible to be sure that a l l were detected. Because the Registry did not receive pathology reports f o r these cases t h i s f i n d i n g indicates a need to improve the n o t i f i c a t i o n procedures. 5.2 The' Quality of the Registry's Information on Fact and Date of Death The findings showed that 'the Registry did not report 71% of the deaths that occurred among the "true" cases of invasive c e r v i c a l cancer diagnosed i n B.C. during 1977, 1978, and 1979. This underreporting drew attention to the need to improve the method of linkage of death n o t i f i c a t i o n s (from the P r o v i n c i a l D i v i s i o n of V i t a l S t a t i s t i c s ) with the Registry's master f i l e . In addition, the findings suggested that the Registry's data on the v i t a l status of cases, i f used to calculate s u r v i v a l rates, would have over-estimated these rates and would have provided poor data f o r evaluating t r e a t -ment of invasive c e r v i c a l cancer i n B.C. I t seems l i k e l y that the under-- 33 -reporting of deaths also occurs for other r e g i s t r a b l e cancers to a s i m i l a r extent. 5.3 The Quality of the Registry's Information on Age, M a r i t a l Status, and Residence The recorded data on the cases' age were usually correct but they were often inaccurate for marital status and residence. They showed that a path-ology report (which was the Registry's source of information for these variables) often gave only age and sex, and gave very l i m i t e d information on other demographic c h a r a c t e r i s t i c s . Other sources of information - CCA.B.C. '. . •. c l i n i c a l chart or private, physician - are, i n f a c t , required to c o l l e c t m a r i t a l status and residence on most cases of invasive c e r v i c a l cancer. In addition, these sources are able to provide data on a wider range of personal variables ( r e l i g i o n , occupation, ethnic o r i g i n ) . Thus, i t was found that the Registry's information provided unreliable data for studies or reports that aim to c l a s s i f y new cases of invasive c e r v i c a l cancer according to demographic features other than age and sex. In conclusion, some of the information (diagnostic, death, and personal) on the cases of invasive c e r v i c a l cancer recorded by the Registry as being diagnosed i n 1977, 1978, and 1979 was inaccurate and incomplete. This occurred because of problems with the system of r e g i s t r a t i o n . The important implication of these findings i s that the Registry has not been able to provide r e l i a b l e data to health care professionals who wish to use i t f o r a v a r i e t y of purposes such as: monitoring the incidence of t h i s disease over time; planning service f a c i l i t i e s f o r invasive c e r v i c a l cancer; and evaluating the p r o v i n c i a l c e r v i c a l screening programme. In addition, i t may be implied that the problems with the Registry's methods of r e g i s t r a t i o n may have caused s i m i l a r errors i n the information recorded by the Registry f o r other types of cancers. REFERENCES Andrews, F., Lineham, J . , and Melcher, D. "C e r v i c a l cancer i n young women", Lancet, 2 (1978), 774-776. Anglesio, E. "Problems i n the i n i t i a t i o n of a cancer r e g i s t r y " , Recent Results i n Cancer Research, 50 (1975), 20-25. Ant e l l o , C. and Lao, C. "United States trends i n mortality from cancer of the cervix", Lancet, 1 (1979), 1038-1042. Barclay, T. "The evaluation of data c o l l e c t i o n procedures - assessment of completeness", Recent Results i n Cancer Research, 50 (1975), 59-75. Barnes, A., Payne, P., and Skeet, R. "The computerized r e g i s t r y " , Recent Results i n Cancer Research, 50 (1975), 26-32. Benedet, J . and Anderson, G. "Ce r v i c a l I n t r a e p i t h e l i a l Neoplasia i n B r i t i s h Columbia: A Comprehensive Program for Detection, Diagnosis, and Treatment", Gynecological Oncology, 12 (1981), 280-291. Beral, V. "Cancer of the cervix: a sexually transmitted i n f e c t i o n ? " , Lancet, 1 (1974), 1040. Berkley, A., L i v o l s i , V., and Schwartz, P. "Advanced squamous c e l l carcinoma of the cervix with recent normal Papanicolaou t e s t s " , Lancet, 2 (1980), 375-376. Berkowitz, R., Ehrmann, R., Lavizzo-Mourey, R., and Knapp, R. "Invasive c e r v i c a l carcinoma i n young women", Gynecologic Oncology, 8.(1979), 311-316. Boyes, D., Worth, A., and F i d l e r , H. "Results of treatment of 4,389 cases of p r e c l i n i c a l c e r v i c a l squamous carcinoma", Journal of Obstetrics and  Gynecology of the B r i t i s h Commonwealth, 77 (1970), 769-780. Boyes, D., Worth, A. and Anderson, G. "Experience with C e r v i c a l Screening i n B r i t i s h Columbia", Gynecological Oncology, 12 (1981), 143-155. CCA.B.C. (Cancer Control Agency of B.C.) Cancer i n B.C. 1978. Annual Report published i n 1980. Elwood, J.M. and Gallagher, R.P. "Surveillance systems for cancer and b i r t h defects i n r e l a t i o n to environmental and occupational hazards: the current s i t u a t i o n and the need for progress." Report to the B r i t i s h Columbia Royal Commission of Inquiry into Uranium Mining i n B r i t i s h Columbia, 1980. F i d l e r , H., Boyes, D. and Worth, A. "The Cytology Programme i n B r i t i s h Columbia", Canadian Medical Association Journal, 86 (1962), 823-830. Fujimoto, I. and Hanai, A. "Cancer R e g i s t r i e s i n Japan", National  Cancer I n s t i t u t e Monograph, 47 (1977), 7-15. - 35 -Gallagher, R. and Elwood, M. "Recent trends i n the recorded incidence and mortality from uterine cancer", National Cancer I n s t i t u t e Monograph, 62 (1982). Grace, M. and Davis, F. "Data adequacy a v a l i d i t y , r e l i a b i l i t y and accuracy", i n Manual f o r Cancer Records O f f i c e r s , ed. A.B. M i l l e r . Ottawa: National Cancer I n s t i t u t e , 1975. Green, G. "Rising c e r v i c a l cancer mortality i n young New Zealand women", New Zealand Medical Journal, 14 February 1979, 89-91. Grundmann, E. "The pros and cons of cancer r e g i s t r a t i o n " , Recent  Results i n Cancer Research, 50 (1975), 52-58. Haenszel, W. "The United States network of Cancer R e g i s t r i e s " , Recent Results i n Cancer Research, 50 (1975), 52-58. IARC (International Agency for Research on Cancer) and IACR (International Association of Cancer R e g i s t r i e s ) . Cancer Incidence i n Five Continents, Volume I I I , Geneva, 1976. IARC (International Agency f o r Research on Cancer) and IACR (International Association of Cancer R e g i s t r i e s ) . Cancer Registration and i t s Techniques.. Lyon, 1978. Knowelden, J . , Mork, T. and P h i l l i p s , A.J. The Registry i n Cancer  Control. Geneva: UICC Technical Report Series, 1970. McBride, M. B r i t i s h Columbia Cancer Registry. Vancouver: CCA.B.C. document, 1981. McGregor, J. and Tepu, S. " C e r v i c a l screening", Lancet, 1 (1974), 1401-1402 and 1221-1222. NCI (National Cancer I n s t i t u t e ) . Manual for Cancer Records O f f i c e r s . Ottawa, 1975. Pedersen, E. "Some uses of the Cancer Registry i n cancer c o n t r o l " , B r i t i s h Journal of Preventive and So c i a l Medicine, 16 (1962), 105-110. P r e n d i v i l l e , W., Guilleband, J . , Bamford, P., Beilby, J . et a l . "Carcinoma of cervix with recent normal Papanicolaou t e s t s " , Lancet, 2 (1980), 853-854. Ravinhar, B. and Pompe-kirn, V. "Experiences of the Cancer Registry i n Slovenia", Recent Results i n Cancer Research, 50 (1975), 98-102. Saxen, E. "Cancer Registry: aims, functions and q u a l i t y c o n t r o l " , Arch. Geschwulstforsch, 50 (1980), 588-597. Staszewski, J . "Cancer r e g i s t r y data versus m o r t a l i t y s t a t i s t i c s " , Recent Results i n Cancer Research, 50 (1975), 103-110. Tuyns, A. "The c o l l e c t i o n of a v a i l a b l e information: p o s s i b i l i t i t e s and l i m i t a t i o n s of i n t e r n a t i o n a l standardization", Recent Results i n Cancer  Research, 50 (1975), 14-19. - 36 -UTCC ^(International Union Against Cancer). Cancer Incidence i n Five  Continents, Vol.1, Geneva, 1966. Walton, R. et a l . "The Walton Report", Canadian Medical Association  Journal, 114 (1976), 2-32. Waterhouse, J. "Strategies for the development of a coherent cancer s t a t i s t i c s system", WHO Quarterly Stats, 33 (1980), 185-195. WHO (World Health Organization). Cancer S t a t i s t i c s . Geneva: Technical Report Series 632, 1979. WHO (World Health Organization), WHO Handbook for Standardized Cancer  Re g i s t r i e s . Geneva: WHO Offset P u b l i c a t i o n , 1976a. WHO (World Health Organization), International C l a s s i f i c a t i o n of Diseases  for Oncology. Geneva, 1976b. Yule, R. "Mortality from carcinoma of the cervix", Lancet, 1 (1978), 1031-1032. - 37; -APPENDIX I GLOSSARY - 38 -GLOSSARY Cancer Control Agency of B.C. (CCA.B.C.) re-evaluation procedure - pathologists at the Cancer Control Agency re-examine a l l s l i d e s of c e r v i c a l biopsies or tissue fragments that have been diagnosed as invasive (or probably invasive) by pathologists from general h o s p i t a l s , p r i o r to treatment. The diagnosis from t h i s procedure i s usually regarded as the most r e l i a b l e f i n a l pathological diagnosis since autopsies on deceased cases of invasive c e r v i c a l cancer are infrequently done i n B.C. Stages of c e r v i c a l cancer: carcinoma i n s i t u - a pre-invasive cancerous l e s i o n that i s l o c a l i z e d to the c e r v i c a l e p i t h -elium. I t shows no behavioural c h a r a c t e r i s t i c s of malignant cancer such as invasion into surrounding connective tissue (stroma) or metastasis. same as carcinoma i n s i t u , however, some of the abnormal c e l l s break through the basement membrane of c e r v i c a l epithelium and i n f i l t r a t e a short distance into the stroma (usually to a depth of l e s s than 1 mm). I t i s believed that t h i s represents the e a r l i e s t stage of invasion. occult-invasive carcinoma - same as carcinoma i n s i t u w i t h m i c r o -invasion. However, the extent of stromal invasion i s much l a r g e r . These patients are asymptomatic and a l e s i o n i s not seen on c l i n i c a l inspection. c l i n i c a l l y invasive carcinoma - a malignant cancer i n which abnormal c e l l s i n f i l t r a t e or destroy the underlying stroma. This l e s i o n produces c l i n i c a l signs and symptoms of c e r v i c a l cancer. carcinoma i n s i t u with microinvasion colposcopy-directed biopsy - c l i n i c i a n v i s u a l i z e s the cervix microscopically by means of a colposcopy; l o c a l i z e s the zone(s) of c e l l atypia; and takes a single or multiple b i t e biopsy of the l e s i o n . - 39 -cone biopsy cytology dysplasia hysterectomy ( i ) r a d i c a l ( i i ) t o t a l ( i i i ) sub-total incidence Papanicolaou test pathology re-evaluation by CCA.B.C. pathologists the removal of a cone of tissue around the external os of the cervix. The apex of the cone extends up the endocervical canal. a microscopic examination of body c e l l s as a means of detecting malignant changes. abnormal, sometimes premalignant, development of c e r v i c a l c e l l s . a s u r g i c a l removal of the uterus. It may be performed ei t h e r abdomin-a l l y or v a g i n a l l y and i s c l a s s i f i e d as r a d i c a l , sub-total or t o t a l . t o t a l removal of the uterus, upper vagina, parametrium p e l v i c lymph nodes, f a l l o p i a n tubes and ovaries. This procedure i s only c a r r i e d out for cancer. removal of the corpus and cervix u t e r i . removal of the uterus at or above the l e v e l of the i n t e r n a l os of the cervix. the number of new cases of cancer that occur per population at r i s k i n a p a r t i c u l a r geographic area within a defined time i n t e r v a l such as a year. d i r e c t c i r c u m f e r e n t i a l scrape of the cervix u t e r i . The material from t h i s procedure i s screened microscopically f o r abnormal c e l l s . examination of tis s u e specimens removed for biopsy or during t r e a t -ment or at autopsy, i n order to diagnose cancer. see CCA.B.C. re-evaluation procedure pathologists. - 40 -APPENDIX II THE ABSTRACT FORM USED IN THIS EVALUATION - 4 1 " IDENTIFICATION INFORMATION: (Not Computerized) SURNAME: GIVEN NAME(S) PREVIOUS SURNAME: REGISTRY NUMBER: CYTOLOGY IDENTIFICATION NUMBER: CCA.B.C. NUMBER: STUDY NUMBER: - 42 -(continued) REGISTRY INFORMATION: STUDY NUMBER: CARD NUMBER: MARITAL STATUS: 1 = single 2 = married 3 = widowed 4 = divorced 5 = separated 9 = unknown • ADDRESS: (B.C. School D i s t r i c t codes) DATE OF BIRTH: PATHOLOGICAL DIAGNOSIS: (ICD-0 code) DATE OF DIAGNOSIS: DIAGNOSTIC METHOD: 2 = pathological 3 = autopsy 4 = c y t o l o g i c a l 5 = r a d i o l o g i c a l 6 = c l i n i c a l 9 = unknown D D M M Y ' Y M M - Y Y • AGE AT DIAGNOSIS: SOURCE OF REPORT: DATE OF DEATH: 00 = not stated 02 = death r e g i s t r a t i o n 03 = private physician 04 = Cancer Control Agency of B r i t i s h Columbia 05 = General H o s p i t a l 07 = Riverview H o s p i t a l 09 = Shaughnessy Hospital 10 = Ex-province 20-40 = pathology laboratories of s p e c i f i c h o s p i t a l s i n B r i t i s h Columbia D D M M Y Y - 43 -(continued) CYTOLOGY PROGRAMME INFORMATION: D D M M Y Y DATE OF BIRTH: l l l l l 1 D D M M Y Y DATE OF DIAGNOSIS: I I I I I 1 METHOD OF DIAGNOSIS: 50 = b i t e biopsy 51 = multiple b i t e biopsy 52 = cone biopsy 60 colposcopic d i r e c t biopsy 86 = hysterectomy t i s s u e 53 = D and C ti s s u e 74 = autopsy 99 = no record SOURCE OF REPORT: (See source of report on page 42) PATHOLOGICAL DIAGNOSIS: 01 = squamous dysplasia 02 = squamous carcinoma i n s i t u 03 = squamous carcinoma 04 = invasive squamous carcinoma 05 = squamous carcinoma i n s i t u , with micro-invasive f o c i 06 = squamous carcinoma - occult invasive 07 = squamous carcinoma c l i n i c a l l y invasive 08 = adenocarcinoma 10 = mixed 11 = other (specify) V.B. C RE-EVALUATION'S PATHOLOGICAL DIAGNOSIS* 01 = squamous dysplasia 02 = squamous carcinoma i n s i t u 03 = squamous carcinoma 04 = invasive squamous carcinoma 05 = squamous carcinoma i n s i t u with micro-invasive f o c i 06 = squamous carcinoma - occult invasive 07 = squamous carcinoma c l i n i c a l l y invasive 08 = adenocarcinoma 10 = mixed 11 - other (specify) These pathology diagnoses were converted into ICD-0 code f or the comparison of the Registry's diagnoses and the best estimate of true diagnosis. - 44. -(continued) CCA.B.C. CLINICAL RECORDS: AGE: ADDRESS: (B.C. School D i s t r i c t codes) MARITAL STATUS: 1 = single 2 = married 3 = widowed 4 = divorced 5 = separated 9 = unknown D D M M DATE OF DEATH: - 45 -APPENDIX III THE METHOD OF CALCULATION OF THE REGISTRY'S ESTIMATE AND OF "THE BEST ESTIMATE" OF THE "TRUTH" AGE STANDARDIZED INCIDENCE RATES OF INVASIVE CERVICAL CANCER IN B.C. APPENDIX III Table 5.1.1 1977 1978 1979 World Registry's + Registry's ^ "Best estimate" ## "Best estimate" * Standard Crude Standardized ~of Crude True of True Population Incidence Incidence Incidence Rates Standardized (IARC) Rates Rates (per 100,000) Incidence Rates (per 100,000) 15 - 44 43,000 13.83 14.11 8.23 8.68 45 - 64 19,000 24.72 24.77 20.00 19.98 65+ 7,000 23.26 24.98 17.44 18.48 15 - 44 43,000 14.64 14.95 8.68 8.60 45 - 64 19,000 17.08 16.97 13.98 13.94 65+ 7,000 21.65 21.37 19.55 19.52 15 - 44 43,000 15.07 16.96 8.61 8.95 45 - 64 19,000 20.43 20.44 17.35 16.87 65+ 7,000 21.42 21.26 13.39 13.48 N.B. For footnotes +, # and ## see page 47. APPENDIX III - continued Table 5.1.2 1977 1978 1979 Standard Registry's + Registry's "Best estimate" # # "Best estimate"^ Population Crude Standardized of Crude True of True (Canadian Incidence Incidence Incidence Rates Standardized population Rates Rates (per 100,000) Incidence Rates i n 1976; i n (per 100,000) thousands) 15 - 44 5296.7 13.83 13.57 8.23 8.07 45 - 64 2243.2 24.72 24.64 20.00 19.99 65+ 1126.9 23.26 23.00 17.44 16.48 15 - 44 5296.7 14.64 14.43 8.68 8.30 45 - 64 2243.2 17.08 17.03 13.98 13.99 65+ 1126.9 21.65 21.50 19.55 19.35 15 - 44 5296.7 15.07 16.36 8.61 8.39 45 - 64 2243.2 20.57- 20.47 17.47 17.08 65+ 1126.9 21.27 21.54 12.28 13.49 N.B. For footnotes +, # and ## see page 47. FOOTNOTES FROM PREVIOUS TWO PAGES + A crude rate, the numerator includes the number of new cases of invasive c e r v i c a l cancer recorded by .the Registry as being diagnosed i n 1977 or 1978 or 1979. Federal census data was used to estimate the denominator. # The Registry's and the best estimate of true age s p e c i f i c incidence rates are adjusted by 5 year age groups to conform to IARC's world standard population and Canada's population i n 1976.* This procedure reduces the e f f e c t of the age structure on B.C.'s population (higher proportion of older people compared to populations i n other regions of North America) on the reported age s p e c i f i c incidence rates. I t also f a c i l i t a t e s comparisons of these rates among other populations. ## The numerator includes a l l the new cases of invasive c e r v i c a l cancer that were found i n t h i s evaluation and the 11 cases that were reg i s t e r e d as being diagnosed with invasive c e r v i c a l cancer, but could not be v e r i f i e d p a t h o l o g i c a l l y i n t h i s evaluation. The federal census was again used to c o l l e c t the numbers f o r the denominator. * An example of the method of c a l c u l a t i o n of these rates for Registry's 1978 figures i s shown below. 1978 15-19 20-24 25-29 30-34 35-39 40-44 Total B.C. Population ( i n 1,000) Number of new cases Incidence rate per 100,000 World Standard Population (proportion within 15 - 44 age group) Contribution to age standardized incidence rate 119.9 2 1.66 .20930 116.0 10 8.62 ,18605 110.6 16 14.46 .18605 98.2 24 24.43 ,13953 76.9 10 13.00 .13953 65.8 24 36.47 .13953 34744 1.60375 2.69028 3.40871 1.81389 5.08866 587.4 86 14.64 (crude fate) 1.0 14.95273 (age standardized rate) 

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