Posted on June 15, 2018
A new international study by scientists from the American Cancer Society, the Harvard T.H. Chan School of Public Health, the National Cancer Institute, and more than 20 other medical centers and organizations finds that higher circulating vitamin D concentrations are significantly associated with lower colorectal cancer risk. This study strengthens the evidence, previously considered inconclusive, for a protective relationship between vitamin D concentration and colorectal cancer. The study appeared online on June 14, 2018, in the Journal of the National Cancer Institute.
The investigators analyzed circulating prediagnostic concentrations of 25-hydroxyvitamin D, the accepted measure of vitamin D status, for over 5,700 colorectal cancer cases and 7,100 controls from 17 cohorts in the United States, Europe, and Asia. A single, widely accepted assay and laboratory was used for new measurements and to calibrate existing measurements. Compared to participants with circulating vitamin D concentrations considered sufficient for bone health, those with deficient concentrations had a 31% higher risk of colorectal cancer during follow-up (an average of 5.5 years). Similarly, concentrations above bone health sufficiency were associated with a 22% lower risk. However, risk did not continue to decline at the highest concentrations. These associations persisted even after adjusting for known colorectal cancer risk factors. Though protective associations were seen in all subgroups examined; the association was noticeably stronger in women than men at concentrations above bone health sufficiency.
Reference: McCullough ML, et al. Circulating Vitamin D and Colorectal Cancer Risk: An International Pooling Project of 17 Cohorts. J Natl Cancer Inst 2018 Jun 14. DOI: 10.1093/jnci/djy087. [Epub ahead of print]