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JAMA. 2017 Mar 28;317(12):1234-1243. doi: 10.1001/jama.2017.2115.

Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women: A Randomized Clinical Trial.

Author information

Creighton University Schools of Nursing, Omaha, Nebraska.
University of California San Diego, Department of Family Medicine and Public Health, La Jolla, California.
Department of Bioinformatics and Computational Biology, MD Anderson Cancer Center, University of Texas, Houston.
GrassrootsHealth, La Mesa, California.



Evidence suggests that low vitamin D status may increase the risk of cancer.


To determine if dietary supplementation with vitamin D3 and calcium reduces the risk of cancer among older women.

Design, Setting, and Participants:

A 4-year, double-blind, placebo-controlled, population-based randomized clinical trial in 31 rural counties (June 24, 2009, to August 26, 2015-the final date of follow-up). A total of 2303 healthy postmenopausal women 55 years or older were randomized, 1156 to the treatment group and 1147 to the placebo group. Duration of treatment was 4 years.


The treatment group (vitamin D3 + calcium group) received 2000 IU/d of vitamin D3 and 1500 mg/d of calcium; the placebo group received identical placebos.

Main Outcomes and Measures:

The primary outcome was the incidence of all-type cancer (excluding nonmelanoma skin cancers), which was evaluated using Kaplan-Meier survival analysis and proportional hazards modeling.


Among 2303 randomized women (mean age, 65.2 years [SD, 7.0]; mean baseline serum 25-hydroxyvitamin D level, 32.8 ng/mL [SD, 10.5]), 2064 (90%) completed the study. At year 1, serum 25-hydroxyvitamin D levels were 43.9 ng/mL in the vitamin D3 + calcium 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 vitamin D3 + calcium group and 64 (5.58%) in the placebo group (difference, 1.69% [95% CI, -0.06% to 3.46%]; P = .06). Kaplan-Meier incidence over 4 years was 0.042 (95% CI, 0.032 to 0.056) in the vitamin D3 + calcium group and 0.060 (95% CI, 0.048 to 0.076) in the placebo group; P = .06. In unadjusted Cox proportional hazards regression, the hazard ratio was 0.70 (95% CI, 0.47 to 1.02). Adverse events potentially related to the study included renal calculi (16 participants in the vitamin D3 + calcium 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).

Conclusions and Relevance:

Among healthy postmenopausal older women with a mean baseline serum 25-hydroxyvitamin D level 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. Further research is necessary to assess the possible role of vitamin D in cancer prevention.

Trial Registration: Identifier: NCT01052051.

[Indexed for MEDLINE]

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