Vitamin D and cancer mortality.

B203

Background: Vitamin D has been hypothesized to reduce cancer mortality. No study, to our knowledge, has examined the relationship between measured serum 25 hydroxy-vitamin D (25(OH)D), the vitamin D status metabolite, and total cancer mortality. Methods: We analyzed mortality follow-up data on 16,818 participants in the Third National Health and Nutrition Examination Survey (NHANES III) who were ≥17 years from 1988 through 2000. Using SUDAAN regression models, we examined the relationship between baseline serum 25(OH)D and total cancer mortality for both genders combined and separately. Because serum was generally collected in the south in cooler months and the north in warmer months, we examined associations by season. Categorical 25(OH)D cut-points were set at 50; 62.5; 80; 100; 120 nmol/, with fewer categories in subgroup analyses. Mortality risk for cancer sites was also assessed. Results: We identified 536 cancer deaths in 146,578 person-years. Total cancer mortality was unrelated to 25(OH)D in the entire population, each seasonal group and both genders. Colorectal cancer mortality was inversely related to 25(OH)D, with levels > 80 nmol/l associated with a 72% risk reduction, compared with < 50 nmol/l, p-trend=0.02. Risk of breast cancer mortality was also reduced, but the number of cases was small (n=28) and the linear trend was nonsignificant. Retinol, which has been hypothesized to impair protection from 25(OH)D, did not modify 25(OH)D effects on total cancer or colorectal mortality. Conclusions: In NHANES III, there was no association between 25(OH)D and total cancer mortality, but there was an inverse relationship with colorectal cancer mortality.