A clinical trial (ClinicalTrials.gov: NCT01052051) of the ability of vitamin D3 and calcium to decrease cancer risk in healthy postmenopausal older women revealed no significant difference in all-type cancer risk at 4 years compared with placebo.

Previous research suggested low levels of vitamin D might increase the risk of developing cancer, so researchers assessed whether supplementation with vitamin D3 and calcium would affect this risk in women aged 55 years and older.

In this 4-year, double-blind, placebo-controlled, randomized clinical trial in 31 rural counties between June 2009 and August 2015, 2303 healthy, postmenopausal women aged 55 years or older were randomly assigned either to the treatment group (n=1156) or to placebo (n=1147).

The treatment group received 2000 IU/day vitamin D3 and 1500 mg/day calcium.

Average age was 65.2 years, average baseline serum 25-hydroxyvitamin D level was 32.8 ng/mL, and 2064 women finished the study.

At year 1, levels of serum 25-hydroxyvitamin D were 43.9 ng/mL in the treatment group and 31.6 ng/mL in the placebo group.

In the treatment group, 3.89% (n=45) of patients received a new diagnosis of cancer, and in the placebo group, 5.58% (n=64) received a new diagnosis of cancer (difference, 1.69%; 95% CI, −0.06 to 3.46; P =.06). All-cause skin cancer risk excluded nonmelanoma skin cancers.

In the treatment group, Kaplan-Meier incidence across 4 years was 0.042 (95% CI, 0.032-0.056). In the placebo group, it was 0.060 (95% CI, 0.048-0.076; P =.06). No significant difference in incidence occurred between the 2 groups.

Reference

1. Lappe J, Watson P, Travers-Gustafson D, et al. Effect of vitamin D and calcium supplementation on cancer incidence in older women: a randomized clinical trial [published online March 28, 2017]. JAMA. doi: 10.1001/jama.2017.2115