Title

Calcium plus vitamin D supplementation and the risk of colorectal cancer

UMMS Affiliation

Department of Medicine, Division of Preventive and Behavioral Medicine

Date

February 2006

Document Type

Article

Subjects

Adenocarcinoma; Aged; Calcium; Calcium Carbonate; Colonic Polyps; Colorectal Neoplasms; Double-Blind Method; Drug Combinations; Female; Follow-Up Studies; Humans; Incidence; Middle Aged; Postmenopause; Proportional Hazards Models; Vitamin D

Abstract

BACKGROUND: Higher intake of calcium and vitamin D has been associated with a reduced risk of colorectal cancer in epidemiologic studies and polyp recurrence in polyp-prevention trials. However, randomized-trial evidence that calcium with vitamin D supplementation is beneficial in the primary prevention of colorectal cancer is lacking.

METHODS: We conducted a randomized, double-blind, placebo-controlled trial involving 36,282 postmenopausal women from 40 Women's Health Initiative centers: 18,176 women received 500 mg of elemental calcium as calcium carbonate with 200 IU of vitamin D3 [corrected] twice daily (1000 mg of elemental calcium and 400 IU of vitamin D3) and 18,106 received a matching placebo for an average of 7.0 years. The incidence of pathologically confirmed colorectal cancer was the designated secondary outcome. Baseline levels of serum 25-hydroxyvitamin D were assessed in a nested case-control study.

RESULTS: The incidence of invasive colorectal cancer did not differ significantly between women assigned to calcium plus vitamin D supplementation and those assigned to placebo (168 and 154 cases; hazard ratio, 1.08; 95 percent confidence interval, 0.86 to 1.34; P=0.51), and the tumor characteristics were similar in the two groups. The frequency of colorectal-cancer screening and abdominal symptoms was similar in the two groups. There were no significant treatment interactions with baseline characteristics.

CONCLUSIONS: Daily supplementation of calcium with vitamin D for seven years had no effect on the incidence of colorectal cancer among postmenopausal women. The long latency associated with the development of colorectal cancer, along with the seven-year duration of the trial, may have contributed to this null finding. Ongoing follow-up will assess the longer-term effect of this intervention. (ClinicalTrials.gov number, NCT00000611.).

Rights and Permissions

Citation: N Engl J Med. 2006 Feb 16;354(7):684-96. Link to article on publisher's site

Related Resources

Link to article in PubMed

PubMed ID

16481636

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