Aspirin, nonsteroidal anti-inflammatory drugs, paracetamol and risk of endometrial cancer: a case-control study, systematic review and meta-analysis.

Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) have been associated with reduced risk of a number of cancer types, however, previous studies of endometrial cancer have yielded inconclusive results. We analyzed data from the Australian National Endometrial Cancer Study (ANECS), a population-based case-control study (1,398 cases, 740 controls). We systematically reviewed all the evidence linking aspirin/NSAIDs use with endometrial cancer and conducted a meta-analysis. For ANECS, unconditional logistic regression was used to estimate odds ratios (OR) adjusting for potential confounders. For the systematic review, we searched Pubmed, Embase, Web of Science and conducted a review of citations from retrieved articles. The meta-analysis risk estimates were pooled using a random-effects model. In our case-control study, women who had ever used aspirin in the last 5 years had a significantly lower risk of endometrial cancer OR = 0.78 [95% confidence interval (CI): 0.63-0.97]. There was a significant inverse dose-response (p-trend <0.001) such that women who reported using ≥2 aspirin/week had almost half the risk OR = 0.54 (0.38-0.78). No significant associations were observed between use of half-aspirin/day, non-aspirin NSAIDs or paracetamol and endometrial cancer risk. The results were similar when examined by cancer subtype. Nine studies were included in the meta-analysis. The overall pooled risk estimate for any versus no use of aspirin was 0.87 (0.79-0.96) with no evidence of heterogeneity. The pooled risk estimate for obese women (BMI ≥ 30 kg/m(2) ) was 0.72 (0.58-0.90) but there was no association for non-obese women. Overall these results suggest that aspirin may reduce the risk of endometrial cancer, particularly among obese women.