Multivitamin use and all-cause and cause-specific mortality in cancer survivors

Background Despite no sufficient evidence on benefits and harms of multivitamin use, cancer survivors use multivitamins as a self-care strategy to improve or maintain health. We examined if multivitamin use was associated with mortality in cancer survivors. Methods 15,936 male and 7026 female cancer survivors in the NIH-AARP Diet and Health Study were included in the analysis. Types and frequency of multivitamin use at on average 4.6 years after cancer diagnosis were assessed. Multivariable-adjusted relative risks (RR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression models. Results Multivitamin use was not associated with lower all-cause mortality risk in all female (RR = 0.94, 95% CI:0.87–1.01 daily vs. no use) or male cancer survivors (RR = 0.96, 95% CI:0.91–1.00); however, a modest inverse association for CVD mortality was observed in female survivors of reproductive cancers (RR = 0.75, 95% CI:0.61–0.92) and male survivors of non-reproductive cancers (RR = 0.81, 95% CI:0.70–0.94). Multivitamin use was also associated with a lower risk of cancer-specific mortality in survivors of skin (RR = 0.65, 95% CI:0.48–0.88) and breast (RR = 0.79, 95% CI:0.65–0.95) cancer. Discussion Multivitamin use may provide a modest survival benefit to some cancer survivors. Cancer care providers should talk with cancer survivors about potential benefits and harms of multivitamin use.