Colorectal Cancer Prevention (PDQ®): Prevention - Health Professional Information [NCI] - Description of the Evidence
Cardiovascular Risks Associated With Celecoxib and Rofecoxib Dose/Drugs continued...
In a large cohort study, an association between recent daily aspirin use and lower-cancer mortality in the gastrointestinal tract (RR = 0.61; 95% CI, 0.47-0.78), liver (RR = 0.52; 95% CI, 0.30-0.93), and bladder (RR = 0.52; 95% CI, 0.28-0.97) were observed among the 100,139 analysis-eligible participants from the CPS II Nutrition Cohort established by the American Cancer Society in 1982. The analysis excluded participants who had a history of cancer in the baseline year or whose records contained incomplete information on aspirin use or smoking, and was based on follow-up questionnaires mailed to participants in 1997 (the baseline year for the analysis), 1999, 2001, and 2003. Mortality follow-up continued through Dec 31, 2008 via automated linkage to the National Death Index vital status and cause of death codes (ICD-10); death certificates were obtained for 99.3% of known deaths.
The WHS, the largest randomized trial of aspirin to date (N = 39,876), found no reduction in the incidence of colon or other cancers during the 10-year active intervention. However, among women who voluntarily participated in extended follow-up (N = 33,682; 16,913 from the intervention group and 16,769 from the placebo group), there was a significant reduction in CRC incidence (HR = 0.58; 95% CI, 0.42-0.8, P < .001) with a median follow-up of 8 years. Calculated from the beginning of the intervention period through the extended follow-up (median, 18 years) an overall reduction in CRC incidence was observed for the WHS (HR = 0.80; 95% CI, 0.67-0.97; P = .021; P = .012 intervention period versus extended follow-up). During the intervention phase, women were randomly assigned to receive either an annual supply of aspirin (100 mg) or placebo, taken every other day. During the extended follow-up, the intervention was discontinued. Protocol compliance and medical incidences were tracked via identical annual questionnaires throughout the 18-year period. Medical record reviews by a panel of experts blinded to random assignment confirmed the endpoints reported. Whereas previously reported meta-analyses of randomized trials of daily aspirin use demonstrated a reduction in colon cancer incidence with extended follow-up, these findings from the WHS demonstrate a similar effect from aspirin taken every other day.