There are several reports of clinical trials of
aspirin in sporadic
colon cancer. However, only one double-blind trial of
aspirin in patients with
familial adenomatous polyposis (FAP) has been reported to date. This double-blind, randomized, placebo-controlled clinical trial was therefore performed to evaluate the influence of low-dose
aspirin enteric-coated tablets (100 mg/day for 6-10 months) in 34 subjects with FAP (17 each in the
aspirin and placebo groups). The increase in mean diameter of colorectal
polyps tended to be greater in the placebo group compared with the
aspirin group, which showed a response ratio, that is,
aspirin response rate (number of subjects with reduced
polyps/total)/placebo response rate (number of subjects with reduced
polyps/total), of 2.33 (95% confidence interval: 0.72-7.55). Subgroup analysis revealed that the number of subjects with a mean baseline
polyp diameter of ≤2 mm, and the diameter and number of
polyps after intervention showed a significant reduction in the
aspirin group. Adverse effects of
aspirin, such as anastomotic
ulcer, aphtha in the large intestine, and progression of
anemia, occurred in three subjects. Moreover, none of the subjects developed
colorectal cancer. The results thus indicated a potential for
aspirin to reduce colorectal
adenoma development in patients with FAP, but careful follow-up is needed to avoid or rapidly counter severe adverse effects.