Folic Acid and Prevention of Colorectal Adenomas

Abstract

To the Editor: In their randomized controlled trial of folic acid for prevention of colorectal adenomas, Dr Cole and colleagues reported an increased risk for advanced colorectal adenoma lesions and adenoma multiplicity in the folic acid group. This difference in risk became statistically significant in the second follow-up interval. The authors also noted that randomized aspirin treatment did not modify the effect of folic acid on adenomas in the first follow-up interval. However, Figure 2 in the article indicates that the aspirin placebo subgroup, but not the 2 active aspirin subgroups (81 mg/d and 325 mg/d), seemed to be associated with an increased frequency of advanced lesions in the folic acid group during the first follow-up interval, although this did not appear to reach statistical significance. The authors did not provide the same information for the second follow-up interval, when the increased risk for advanced lesions among the folic acid group became more prominent. We suggest that the authors assess whether this possible interaction between aspirin and folic acid intake exists in the second follow-up interval, because it is possible that a residual effect of 3 years of aspirin intake would persist for another 3 to 5 years.