Plasma 25-hydroxyvitamin D and risk of pancreatic cancer.

BACKGROUND

Laboratory studies suggest that vitamin D may inhibit pancreatic cancer cell growth. However, epidemiologic studies of vitamin D and pancreatic cancer risk have been conflicting.

METHODS

To determine whether prediagnostic levels of plasma 25-hydroxyvitamin D (25[OH]D; IDS Inc.; enzyme immunoassay) were associated with risk of pancreatic cancer, we conducted a pooled analysis of nested case-control studies with 451 cases and 1,167 controls from five cohorts through 2008. Median follow-up among controls was 14.1 years in Health Professionals Follow-Up Study (HPFS), 18.3 years in Nurses' Health Study (NHS), 25.3 years in Physicians' Health Study (PHS), 12.2 years in Women's Health Initiative-Observational Study (WHI), and 14.4 years in Women's Health Study (WHS). Logistic regression was used to compare the odds of pancreatic cancer by plasma level of 25(OH)D.

RESULTS

Mean plasma 25(OH)D was lower in cases versus controls (61.3 vs. 64.5 nmol/L, P = 0.005). In logistic regression models, plasma 25(OH)D was inversely associated with odds of pancreatic cancer. Participants in quintiles two through five had multivariable-adjusted ORs (95% confidence intervals) of 0.79 (0.56-1.10), 0.75 (0.53-1.06), 0.68 (0.48-0.97), and 0.67 (0.46-0.97; P(trend) = 0.03), respectively, compared with the bottom quintile. Compared with those with insufficient levels [25[OH]D, <50 nmol/L], ORs were 0.75 (0.58-0.98) for subjects with relative insufficiency [25[OH]D, 50 to <75 nmol/L] and 0.71 (0.52-0.97) for those with sufficient levels [25[OH]D, ≥ 75 nmol/L]. No increased risk was noted in subjects with 25(OH)D ≥100 nmol/L, as suggested in a prior study. In subgroup analyses, ORs for the top versus bottom quartile of 25(OH)D were 0.72 (0.48-1.08) for women, 0.73 (0.40-1.31) for men, and 0.73 (0.51-1.03) for Whites.

CONCLUSIONS

Among participants in five large prospective cohorts, higher plasma levels of 25(OH)D were associated with a lower risk for pancreatic cancer.

IMPACT

Low circulating 25(OH)D may predispose individuals to the development of pancreatic cancer.