Clinical trials have shown that calcium supplementation modestly decreases the risk of colorectal adenomas.
In this study, investigators from the United States evaluated patients from the Calcium Polyp Prevention Study; a randomized, double-blind, placebo-controlled chemoprevention trial in patients with a recent colorectal adenoma.
A total of 930 patients were randomly assigned to either calcium carbonate (1200 mg per day) or placebo.
The team performed follow-up colonoscopies at 1 and 4 years after each patient’s qualifying examination.
They used a general estimating equation and generalized linear regression analyses to assess the effect of calcium treatment on the risk of hyperplastic polyps, tubular adenomas, and advanced lesions.
The team also compared the calcium treatment effects for various types of polyps with that for tubular adenomas.
In addition, the investigators examined the interaction between calcium treatment and baseline intake of dietary calcium, fat, and fiber.
The investigators found that the calcium risk ratios were 0.82 for hyperplastic polyps, 0.89 for tubular adenomas, and 0.65 for histologically advanced neoplasms.
The team did not identify any statistically significant differences between the risk ratio for tubular adenomas and other types of polyps.
Dr Kristin Wallace and colleagues concluded, “Our results suggest that calcium supplementation may have a more pronounced anti-neoplastic effect on advanced colorectal lesions than on other types of polyps”.