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Incidence and profile of skin cancer in patients undergoing ultraviolet-B phototherapy

University of British Columbia

Background: Ultraviolet (UV) phototherapy is an important treatment option in Canada for skin diseases. However, the long-term risk of skin cancer, has not been adequately studied and quantified in the published literature. Objectives: The objectives include i) to create an electronic database for patients receiving phototherapy at the Psoriasis and Phototherapy Clinic, Skin Care Center, Vancouver; ii) to explore incidence of skin cancers including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma in patients with UVB therapy; iii) to evaluate skin cancers by anatomical distribution and skin type; iv) to compare incidence rate of skin cancers in patients with phototherapy and British Columbia general population; v) to correlate total treatment session, cumulative dosage with skin cancer risk; vi) to estimate correlation between skin type and narrow-band UVB (NB-UVB) minimal erythemal dose. Methods: A retrospective chart review was conducted on patients receiving UV therapy from May 1977 to November 2018. These patients were identified via medical charts at the Psoriasis and Phototherapy Clinic. Pathological ascertainment of basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma for these patients was verified through linkage with an interhospital pathology database for the British Columbia Lower Mainland regional health authorities. Results: A total of 3,506 patients (1,999 male and 1,507 female) were analyzed for an average of 7.1 years. A total of 170 new skin cancers developed in 79 patients after receiving UVB phototherapy without systemic psoralen plus UVA. Male patients had significantly lower BCC incidence compared to BC general population (Z scores<0, p<0.05). Sub-analysis of multivariate logistic regression and survival analysis indicated no statistically significant correlations between cumulative dosage and the risk of skin cancer. Odds ratios of developing skin cancer for the upper vs lower tercile group for broad-band UVB and narrow-band UVB cumulative dosages were 0.82 (p=0.80) and 0.64 (p=0.57). In addition, there was no dose-related correlation for UVB treatment dosage and skin cancer development. Conclusion: No increasing skin cancer incidence and risk was found in UVB phototherapy patients compared to general population. Regular UVB treatment might even protect patients from keratinocyte carcinoma, especially BCC, development.

Text

2020-05-04

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/74301

Experimental Medicine

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/