Use of nonsteroidal anti-inflammatory drugs and incidence of colorectal cancer - A population-based study

Background: Previous observational studies have provided limited informatio n on the effect of specific nonsteroidal anti-inflammatory drugs (NSAIDs) a nd different patterns of use (duration and dose) on the incidence of colore ctal cancer. Objective: To determine how patterns of use (duration, dose, and specific d rug) of NSAIDs affect incidence of colorectal cancer. Design: Population-based retrospective cohort study. Setting: Tennessee Medicaid Program, 1985-1992. Subjects: Enrollees (n = 104 217) aged 65 years or older with at least 5 ye ars of enrollment. Main Outcome Measures: Incident histologically confirmed colorectal cancer. Results: Users of nonaspirin NSAIDs for at least 48 months of the previous 5 years had a relative risk (RR) of 0.49 (95% confidence interval [CI], 0.2 4-1.00) for colon cancer when compared with those with no use of NSAIDs. Am ong those with more than 12 months of cumulative use, those using NSAIDs in the past year (recent users) had an RR of 0.61 (95% CI, 0.48-0.77), wherea s those with no recent use had an RR of 0.76 (95% CI, 0.50-1.15). No specif ic NSAID offered a unique protective effect and low doses of NSAIDs appeare d to be at least as effective as higher doses. Protection was most pronounc ed for right-sided lesions. The RR among recent users with more than 12 mon ths of cumulative use was 0.81 (95% CI, 0.49-1.32) for rectal cancer, 0.77 (95% CI, 0.55-1.08) for left-sided colon cancer, and 0.48 (95% CI, 0.34-0.6 8) for right-sided colon cancer. Conclusions: In this elderly population, long-term use of nonaspirin NSAIDs nearly halved the risk of colon cancer. This study was consistent with pre vious studies that suggest that duration of use but not daily dose of NSAID s is an important factor for chemoprevention. Our data also suggest that th e protective effect is shared by most NSAIDs, and not confined to a small n umber of these drugs.