Association of 25-hydroxyvitamin D with liver cancer incidence and chronic liver disease mortality in Finnish male smokers of the ATBC study.

Background: Although circulating 25-hydroxyvitamin D [25(OH) D] concentrations were linked to liver cancer and chronic liver disease (CLD) in laboratory studies, few epidemiologic studies have addressed the associations. Methods: Within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, we measured 25(OH) D in baseline serum of 202 incident liver cancer cases and 225 CLD deaths that occurred during nearly 25 years of follow-up, and 427 controls. ORs and 95% confidence intervals (CIs) were estimated using unconditional logistic regression. We examined predetermined clinically defined cut-points, and season-specific and season-standardized quartiles. Results: Low serum 25(OH) D concentrations were associated with higher risk of liver cancer (< 25 nmol/L vs. >= 50 nmol/L: 1.98; 95% CI, 1.22-3.20; Ptrend across categories = 0.003) and CLD mortality (1.93; 95% CI, 1.23-3.03; Ptrend = 0.006) in models adjusted for age and date of blood draw. After additional adjustment for body mass index, diabetes, smoking, and other potential confounders, the association remained statistically significant for liver cancer (1.91; 95% CI, 1.16-3.15; P-trend = 0.008), but was somewhat attenuated for CLD mortality (1.67; 95% CI, 1.02-2.75; Ptrend = 0.05). Associations were similar for analyses using season-specific and season-standardized quartiles, and after excluding participants with diabetes, or hepatitis B or C. Conclusions: Our results suggest a possible preventive role for vitamin D against liver cancer and CLD, although the importance of the liver for vitamin D metabolism and the lack of information about underlying liver disease makes reverse causality a concern. Impact: Future studies are needed to evaluate associations of vitamin D with liver cancer and liver disease in other populations, particularly those with a different constellation of risk factors. (C) 2018 AACR.