Sun Exposure and the Risk of Prostate Cancer in the Singapore Prostate Cancer Study: a Case-control Study


Background: Most of the epidemiology studies on the effects of sun exposure and prostate cancer wereconducted among the temperate countries of North America and Europe. Little is known about the influenceon Asian populations. The purpose of current study was to evaluate any association of sun exposure with riskof prostate cancer in Chinese, Malays and Indians who reside in the tropics.
Methods: The Singapore ProstateCancer Study is a hospital-based case-control study of 240 prostate cancer incident cases and 268 controlsconducted in Singapore between April 2007 and May 2009. Detailed information on outdoor activities in thesun, skin colour, sun sensitivity and other possible risk factors were collected in personal interviews. Cases werefurther classified by Gleason scores and TNM staging. Odds ratios (OR) and 95% confidence intervals (CI) werecalculated using unconditional logistic regression analysis, adjusted for age, ethnicity, education, family historyof any cancers, BMI and skin colour.
Results: We found that prostate cancer risk was increased in subjects withblack/dark-brown eyes (OR 5.88, 95%CI 3.17-10.9), darker skin colour e.g. tan/dark brown/black (OR 7.62,95%CI 3.41-17.0), frequent sunburn in lifetime (OR 4.30, 95%CI 1.7-11.2) and increased general sun exposure inadulthood per week (OR 2.03, 95%CI 1.09-3.81). The increased risk was consistent for high grade tumours andadvanced stage prostate cancers.
Conclusion: The findings from this study suggest that excessive sun exposureis a risk factor for prostate cancer in Asians.