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UBC Theses and Dissertations

Pre-diagnosis morbidity related to health care utilization in young women with breast cancer : a matched case-control study Julia, Dunn


Background- Early-onset breast cancer is the leading cause of cancer deaths in Canadian women aged 30-39. There is much that is not known about what causes this disease. Many of the potential risk factors associated with this disease have strong hormonal, inflammatory or immunologic mechanisms, and may be reflected in morbidity prior to diagnosis. Research Question- This study addresses the question: Is morbidity in the five years prior to diagnosis associated with an increased risk of early-onset breast cancer? The primary objective of this study is to describe the extent and patterns of non-cancer morbidity in women diagnosed with breast cancer by age 40, and to compare them with similarly-aged women without a breast cancer by that age. Methods- A total of 1132 female breast cancer patients diagnosed in British Columbia from 1999 to 2008 inclusive were identified through the provincial cancer registry; 1302 female birth year-matched comparators were randomly selected from the provincial health insurance registry. Linked provincial registry, clinical, and healthcare administrative data were used to examine the morbidity experience of subjects for five years before the breast cancer diagnosis or matched date among controls. Morbidity was measured using Johns Hopkins ACG System Aggregated Diagnostic Group (ACG) codes. A multivariate conditional logistic regression model estimated the association between ACG grouping and breast cancer incidence using a one-tailed significance level of α = 0.05. Results- Five (pregnancy, prevention, signs and symptoms/major, unstable orthopedic and stable eye) of 32 ACGs were statistically significantly higher among women with breast cancer than the population sample in at least two of the five years prior to diagnosis. The ACG for asthma produced results of interest. The majority of significant results were observed two to three years preceding diagnosis. Discussion- The increased rate of major signs and symptoms, and asthma, in particular, among young women with breast cancer may point to important underlying risks in this population. Given the number of breast cancer risk factors that have strong associations with hormonal mechanisms, such as reproductive health, hormonal conditions may determine whether lifestyle and other risk factors lead to carcinogenesis.

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