We identified four clinical trials that satisfied the inclusion criteria:
the Aspirin/Folate Polyp Prevention Study (AFPPS) ( 10 ), the
Colorectal Adenoma Prevention Study [Cancer and Leukemia
Group B (CALGB) 9270] ( 11 ), the United Kingdom Colorectal
Adenoma Prevention (ukCAP) Study ( 12 ), and the Association
pour la Prevention par l ’ Aspirine du Cancer Colorectal (APACC)
Study ( 13 ). Table 1 summarizes the trial designs. Three of the four
trials (AFPPS, ukCAP, and APACC) recruited participants with a
recent history of sporadic colorectal adenoma and excluded individuals
with a history of invasive large-bowel cancer, and one trial
(CALGB 9270) specifically recruited patients who had been