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.
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.
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