Nonsteroidal antiinflammatory drugs and colorectal cancer

Background. The association between the use of nonsteroidal antiinflammatory drugs (NSAID) and large bowel cancer was examined in a hospital‐based case‐control study of 511 patients with colorectal cancer and 500 age‐sex matched control subjects. Methods. Regular NSAID use was defined as at least 3 times per week for 1 or more years before the date of hospital admission. Odds ratios (OR) were calculated by the duration of NSAID use and according to the medical reasons given for taking NSAIDs. Results. The prevalences of regular NSAID use were 15% for male patients, 8% for female patients, and 20% for control subjects. Overall, NSAID use was associated with a statistically significant risk reduction in men (OR = 0.64; 95% confidence interval [CI], 0.42–0.97) and in women (OR = 0.32; 95% CI, 0.18–0.57). The estimate decreased with duration among men but increased with duration among women. The risk reduction among patients who took NSAIDs to prevent heart disease was 0.67 (95% CI, 0.38–1.13) for men and 0.43 (95% CI, 0.12–1.59) for women. For treating headache pain, the OR was 0.5 (95% CI, 0.23–1.09) for men and 0.64 (95% CI, 0.25–1.62) for women. The use of NSAID was not found to be associated with the stage of cancer at diagnosis. The OR for daily acetaminophen use was 1.07 (95% CI, 0.35–3.23) for men and 0.59 (95% CI, 0.27–1.25) for women. Conclusions. The regular use of NSAIDs was associated with an overall significant risk reduction of colorectal cancer in men and in women. Among female patients, the greater protective effect associated with short term NSAID use compared with long term NSAID use may reflect a sampling bias.