Vitamin D Supplementation and Cancer Risk
In a trial reported in The New England Journal of Medicine by Manson et al, vitamin D supplementation was found to have no benefit in reducing risk of invasive cancer vs placebo over 5 years of follow-up.
Study Details
The trial was a randomized, placebo-controlled trial, with a two-by-two factorial design, of vitamin D3 and marine n-3 fatty acids in the primary prevention of cardiovascular disease and cancer among men 50 years of age or older and women 55 years of age or older. A total of 25,871 participants were randomly assigned between November 2011 and March 2014 to vitamin D3 (cholecalciferol) at a dose of 2000 IU/d (n = 12,927) or placebo (n = 12,944). The primary endpoint was the incidence of invasive cancer of any type.
Risk of Cancer
Median follow-up was 5.3 years. Invasive cancer was diagnosed in 793 participants in the vitamin D group vs 824 in the placebo group (hazard ratio [HR] = 0.96, P = .47). No significant differences between groups were observed in the incidence of breast cancer (124 vs 122 participants, HR = 1.02, 95% confidence interval [CI] = 0.79–1.31), prostate cancer (192 vs 219, HR = 0.88, 95% CI = 0.72–1.07), or colorectal cancer (51 vs 47, HR = 1.09, 95% CI = 0.73–1.62). Death from cancer occurred in 154 vs 187 participants (HR = 0.83, 95% CI = 0.67-1.02).
In post hoc analysis excluding the first 2 years of follow-up, there was no significant difference in incidence of invasive cancer of any type (490 vs 522, HR = 0.94, 95% CI = 0.83–1.06), but a potential reduction in risk of death from cancer in the vitamin D group (112 vs 149, HR = 0.75, 95% CI = 0.59–0.96).
With regard to cardiovascular endpoints, there were no differences in the incidence of major cardiovascular events (HR = 0.97, P = .69) or death from cardiovascular causes (HR = 1.11, 95% CI = 0.88–1.40).
The investigators concluded, “Supplementation with vitamin D did not result in a lower incidence of invasive cancer or cardiovascular events than placebo.”
Disclosure: The study was funded by the National Institutes of Health and others. The study authors’ full disclosures may be found at nejm.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
