When compared with the non-NSAID cohort, the second cancer incidence was significantly lower in patients taking non-COX-2 inhibitors (adjusted SHR 0.67, 95% CI 0.47–0.94) and in those receiving multiple NSAIDs during follow-up (adjusted SHR 0.55, 95% CI 0.37–0.84). This evidence concerns the gene PTGS2 and cancer.