Cancer Res. 2010 Sept
Freedman DM, Looker AC, Abnet CC, Linet MS, Graubard BI.
Division of Cancer Epidemiology and Genetics, National Cancer Institute.
Vitamin D has been hypothesized to protect against cancer. We followed 16,819 participants in NHANES III from 1988 through 2006, expanding upon an earlier NHANES III study (1988-2000). Using Cox proportional hazard regression models, we examined risk related to baseline serum 25-hydroxyvitamin D (25(OH)D) for total cancer mortality, in both sexes, and by racial/ethnic groups, as well as for site-specific cancers. Because serum was collected in the south in cooler months and the north in warmer months, we examined associations by collection season ("summer/higher latitude" and "winter/lower latitude"). We identified 884 cancer deaths during 225,212 person-years. Overall cancer mortality risks were unrelated to baseline 25(OH)D status in both season/latitude groups, and in non-Hispanic whites, non-Hispanic blacks, and Mexican-Americans. In men, risks were elevated at higher levels (e.g., for ?100 nmol/L, RR= 1.85 (95% CI=1.02-3.35) compared to <37.5 nmol/L).
Although risks were unrelated to 25(OH)D in all women combined, risks significantly decreased with increasing 25(OH)D in the summer/higher latitude group (for ?100 nmol/L, RR= 0.52 (95% CI=0.25-1.15) compared to <37.5 nmol/L, P-trend=0.03, based on continuous values). We also observed a suggestion of an inverse association with colorectal cancer mortality (P-trend=0.09) and a positive association with lung cancer mortality among males (P-trend=0.03). Our results do not support a the hypothesis that 25(OH)D is associated with reduced cancer mortality.
Although cancer mortality in females was inversely associated with 25(OH)D in the summer/higher latitude group, cancer mortality at some sites was increased among men with higher 25(OH)D. These findings argue for caution before increasing 25(OH)D levels to prevent cancer. PMID: 20847342