Elevated 25-hydroxyvitamin D concentrations are inversely correlated with cancer risk, according to a study published in the BMJ.
Sanjeev Budhathoki, staff scientist of the Epidemiology and Prevention Group, at the Center for Public Health Sciences, National Cancer Center in Tokyo, and associates conducted a nested case-group study within the Japan Public Health Center-based Prospective Study group to determine the correlation between circulating plasma 25-hydroxyvitamin D concentration and overall or specific cancer risks.
The primary outcome was the incidence of overall or specific cancer. The investigators selected 4044 random subgroup volunteers to match the 3301 cancer patients and measured the concentration of plasma 25-hydroxyvitamin D with an enzyme immunoassay.
Participants were sorted into quarters based on gender- and season-specific distributions of 25-hydroxyvitamin D, and hazard models were calculated using statistical analysis. Of the separated groups, the lowest quarter was used as the reference.
The researchers reported that increased circulating 25-hydroxyvitamin D concentrations were negatively correlated with total cancer risks for the second, third, and fourth quarter groups. Using the first quarter’s multivariable adjusted hazard ratio (HR) as the reference, the investigators found that the second, third, and fourth quarters resulted in a reduced risk for cancer (HR, 0.81, 0.75, and 0.78, respectively).
Though the investigation resulted in hazard ratios for liver cancer in the 3 higher quarters as 0.70, 0.65, and 0.45, respectively, eliminating cancer incidents of one site from the total cases did not significantly alter the hazard ratios.
“Our findings support the hypothesis that vitamin D may confer protection against the risk of cancer,” the authors wrote.
“Nevertheless, the lower risk associated with higher circulating vitamin D concentration seemed to show a ceiling effect, which may suggest that although maintaining an optimal 25-hydroxyvitamin D concentration is important for prevention of cancer, having a concentration beyond this optimal level may provide no further benefit,” continued the investigators. “Future studies are needed to clarify the dose-response pattern and the optimal concentrations for cancer prevention.”
- Budhathoki S, Hidaka A, Yamaji T, et al. Plasma 25-hydroxyvitamin D concentration and subsequent risk of total and site specific cancers in Japanese population: large case-cohort study within Japan public health center-based prospective study cohort. BMJ. 2018 March 7. doi: 10.1136/bmj.k671