UV Exposure, Vitamin D, and Prostate Cancer Risk in African Americans

Abstract

Abstract : African American men have the highest incidence of prostate cancer compared to other ethnic groups. This cohort also tends to present at an advanced stage with aggressive histology and increased cancer-related mortality. There is accumulating evidence that vitamin D may be an important determinant of the occurrence and progression of prostate cancer. Because the prostate cancer mortality rate increases significantly as the availability of ultraviolet (UV) radiation exposure decreases, and the synthesis of vitamin D depends on UV radiation, it was hypothesized that vitamin D deficiency is a risk factor for prostate cancer. Research suggests that vitamin D has a protective effect on prostate cancer. The goal of this study is to explore the effects of UV exposure, serum Vitamin D, and skin color on prostate cancer risk in a large case-control study of African American men >/= 40 years of age from the Washington, DC area. The aims are to recruit 76 prostate cancer cases and 152 age- and ethnicity-matched controls; assess UV exposure in patients and controls; measure modifying factors of UV exposure (i.e., skin color, serum 25-OH Vitamin D, and gene variation in Vitamin D metabolism); and (4) determine if UV exposure and modifying factors act alone or interact to affect prostate cancer risk in African American men. To date, 27 African American males with histologically diagnosed adenocarcinoma of the prostate have been identified. Subjects have a PSA greater than 2.5 ng/ml and a positive DRE. They were recruited through Howard University Hospital. Nine age- and ethnicity-matched controls have been recruited through the free screenings program at Howard University Cancer Center. For patients and controls, the authors have collected medical histories and blood samples for gene testing; serum circulating levels of 25-OH Vitamin D have been measured by enzyme immunoassay; and subjects have completed food frequency and UV exposure questionnaires.