No Reduction in Recurrent Colorectal Adenomas With Vitamin D and Calcium Supplementation
In a trial reported in The New England Journal of Medicine, Baron et al found that daily vitamin D and calcium supplementation did not reduce recurrence of colorectal adenomas in patients with recently diagnosed adenomas and no known polyps remaining after complete colonoscopy.
Study Details
In the double-blind trial, 2,259 patients from 11 U.S. sites were randomly assigned between July 2004 and July 2008 to receive daily vitamin D3 at 1,000 IU (n = 420), calcium as carbonate at 1,200 mg (n = 419), both (n = 421), or neither (2 placebo tablets, n = 415) in a partial 2×2 factorial design. Women could choose to receive calcium plus randomization to vitamin D or placebo.
Follow-up colonoscopy was anticipated to be performed at 3 or 5 years, according to endoscopist recommendation. The primary endpoint was adenomas diagnosed in the interval from randomization through anticipated surveillance colonoscopy.
Patients agreed to avoid taking study treatments outside the trial. However, due to increasing publicity regarding potential benefits of the treatments, use of personal supplementation up to 1,000 IU of vitamin D and 400 mg of elemental calcium were was allowed, but discouraged, beginning in April 2008. Among 2,251 patients with available data, 4.4% reported in at least two semiannual interviews that they took personal daily vitamin D of ≥ 1,000 IU, 3.3% reported taking calcium ≥ 400 mg, and 3.5% reported taking vitamin D at 500 to < 1,000 IU.
Adenoma Rates
Overall, only 3.0% of patients did not have colonoscopic examination at ≥ 1 year after randomization; 77% had surveillance colonoscopic examination within 6 months before or after the anticipated follow-up at 3 or 5 years.
Patients randomized to receive vitamin D had a mean net increase in serum 25-hydroxyvitamin D of 7.83 ng/mL vs patients receiving placebo. Overall, 43% of participants had at least one adenoma detected during follow-up. Rates were 42.8% with vs 42.7% without vitamin D (adjusted risk ratio [RR] = 0.99, 95% confidence interval [CI] = 0.89–1.09), 45.3% with vs 47.6% without calcium (RR = 0.95, 95% CI = 0.85–1.06), 40.3% with vitamin D plus calcium vs 39.5% with calcium alone (RR = 1.01, 95% CI = 0.88–1.15), and 45.7% with vitamin D plus calcium vs 48.2% with neither (RR = 0.93, 95% CI = 0.80–1.08).
For one or more advanced adenomas, rates were 9.5% with vs 9.4% without vitamin D (RR = 0.99, 95% CI = 0.75–1.29), 10.5% with vs 10.1% without calcium (RR = 1.02, 95% CI = 0.76–1.38), 8.6% with vitamin D plus calcium vs 9.5% with calcium alone (RR = 0.89, 95% CI = 0.63–1.26), and 9.6% with vitamin D plus calcium vs 9.2% with neither (RR = 0.99, 95% CI = 0.63-1.56).
The investigators concluded: “Daily supplementation with vitamin D3 (1000 IU), calcium (1200 mg), or both after removal of colorectal adenomas did not significantly reduce the risk of recurrent colorectal adenomas over a period of 3 to 5 years.”
John A. Baron, MD, of the University of North Carolina at Chapel Hill, is the corresponding author for The New England Journal of Medicine article.
The study was funded by the National Cancer Institute. For full disclosures of the study authors, visit www.nejm.org.
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