Vitamin D and calcium supplementation not effective for lowering cancer risk in postmenopausal women

Among healthy, postmenopausal older women, the incidence of all-type cancer was not decreased with vitamin D₃ and calcium supplementation at 4 years, according to a study published in JAMA.

Joan Lappe, PhD, RN, from the Creighton University School of Nursing in Omaha, Nebraska, and colleagues, conducted a randomized clinical trial to evaluate the effect of supplementation with vitamin D₃ and calcium on risk of incident all-type cancer in healthy older women. The double-blind, placebo-controlled, population-based trial took place in 31 rural counties from June 24, 2009, to August 26, 2015. A total of 2303 postmenopausal women aged 55 years and older were included, with 1156 (50.2%) in the treatment group and 1147 in the placebo group. Duration of treatment was 4 years.

The treatment group (vitamin D₃ + calcium) received vitamin D₃ (cholecalciferol; 2000-IU capsule, once daily) and calcium carbonate (500-mg tablet, 3 times daily), and the placebo group received identical placebos. The primary outcome was first diagnosis of any type of cancer (excluding nonmelanoma skin cancers). Prespecified secondary analyses were planned for common specific types of cancer including cancers of the breast, lung, and colon, and lymphoma, leukemia, and myeloma. Other secondary outcomes included hypertension, cardiovascular disease, osteoarthritis, colonic adenomas and diabetes, upper respiratory tract infections, and falls.

Of 2303 participants enrolled, 2064 (89.6%; 89.0% of the treatment group, 90.2% of the placebo group) completed the study. The mean age was 65.2 years, and most participants (99.5%) self-identified as non-Hispanic white race. Of those not completing the study, 16 participants (7 in the vitamin D₃ + calcium group and 9 in the placebo group) died during the study.

At year 1, serum 25-hydroxyvitamin D levels were 43.9 ng/mL in the treatment group and 31.6 ng/mL in the placebo group. A new diagnosis of cancer was confirmed in 109 participants, 45 (3.89%) in the treatment group and 64 (5.58%) in the placebo group. Kaplan-Meier incidence over 4 years was 0.042 in the treatment group and 0.060 in the placebo group. Adverse events potentially related to the study included renal calculi (16 participants in the treatment group and 10 in the placebo group), and elevated serum calcium levels (6 in the vitamin D₃ + calcium group and 2 in the placebo group).

“In this RCT involving healthy postmenopausal older women with mean serum 25(OH)D levels of 32.8 ng/mL, supplementation with vitamin D₃ and calcium compared with placebo did not result in a significantly lower risk of all-type cancer at 4 years,” said the authors. 

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. JAMA. 28 March 2017. doi: 10.1001/jama.2017.2115