Risk of cancer in a large cohort of nonaspirin NSAID users:: a population-based study

There is increasing evidence of an inverse association between use of nonsteroidal anti-inflammatory drugs ( NSAIDs) and risk of colorectal cancer. However, data regarding other cancer sites are limited. Using data from the population-based North Jutland Prescription Database and the Danish Cancer Registry, we compared cancer incidence among 172 057 individuals prescribed nonaspirin NSAIDs with expected incidence ( based on county-specific cancer rates) during a 9-year study period. A total of 6081 incident cancer cases were diagnosed among NSAID users vs 5722 expected ( standardised incidence ratio ( SIR) 1.1, 95% confidence interval (CI) 1.0 - 1.1). The SIRs for colon and rectal cancer among persons who obtained 10 or more prescriptions were 0.7 ( 95% CI 0.6 - 0.9) and 0.6 ( 95% CI 0.4 - 0.9), respectively. Similarly, reduced risk estimates were found for stomach ( SIR 0.7, 95% CI 0.4 - 1.1) and ovarian cancer ( SIR 0.7, 95% CI 0.4 - 1.0). Standardised incidence ratios for other cancers among those with 10 or more prescriptions tended to be close to 1.0, except for lung, kidney, and prostate cancers with SIRs of 1.3 ( 95% CI 1.1 - 1.6), 1.4 ( 95% CI 0.9 - 2.1), and 1.6 ( 95% CI 1.3 - 2.0), respectively. We found protective associations of NSAIDs against colon, rectal, stomach, and ovarian cancer. Reasons for the increased risk for some cancer sites are not clear.