Purpose: Inhibition of COX-2 enzymes is a frequently suggested mechanism for the beneficial effects of NSAIDs on carcinogenesis. The aim of this study was to explore the role of cumulative NSAID use on four common non-skin related cancers and modification by COX-2 G-765C genotype. Patients and methods: 7621 participants of The Rotterdam Study were included. In a mean follow up period of 10 years, 720 color