Solar Ultraviolet Radiation's Effect on Prostate Cancer Risk and the Role of being Overweight or Obese: A Canadian Cohort Study
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Authors
Khan, Momtafin
Date
Type
thesis
Language
eng
Keyword
prostate cancer , epidemiology , obesity , solar ultraviolet radiation , canadian study
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Abstract
Background: While solar ultraviolet radiation (UVR) exposure is a known cause of melanoma, epidemiologic studies have examined the association between solar UVR exposure and prostate cancer (PCa) risk, depicting a potential protective effect of increased solar UVR exposure. The relationship is potentially modified by obesity as it impacts vitamin D metabolism. Only two previous Canadian studies have investigated solar UVR exposure and PCa risk. This study’s objectives were to investigate the relationship between three different solar UVR exposures and PCa risk in Canada.
Methods: This prospective cohort study used data from three cohorts within the Canadian Partnership for Tomorrow’s Health, linked to cancer registries or administrative data to identify cancer cases. Questionnaires were completed at baseline to obtain information on sun exposure, occupation, and PCa risk factors. A cox proportional hazards model was used to estimate hazard ratios (HR) for time spent in the sun and ambient UVR exposure. A nested case-cohort study was created to study occupational UVR, using a weighted cox proportional hazards model. Both models used age as the timescale. Interactions by ambient UVR, sun protection, vitamin D intake, and calcium intake were explored. For further exploration, a combined solar UVR variable was created, comprised of time spent in the sun and occupational UVR.
Results: No statistically significant associations were observed between solar UVR and PCa risk. One statistically significant observation with normal BMI, between time spent in the sun categories of 1 to < 2 hours per day and < 1 hour per day (HR: 0.64, 95% CI: 0.44, 0.92). No statistically significant interactions were observed with occupational UVR and time spent in the sun with ambient UVR, sun protection, vitamin D and calcium. No association was observed between combined solar UVR and PCa risk.
Conclusion: Overall, results of this study do not support a relationship between solar UVR exposure in Canada to PCa risk. This project adds to the Canadian literature examining the relationship between solar UVR exposure and PCa risk and with three measures of solar UVR exposure. Further research should expand on this study with greater variation within the solar UVR exposure categories.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.