Inflammatory mediators, such as prostaglandins and histamines can cause pain. Non steroid anti-inflammatory drugs (NSAIDs) have been indicated to reduce pain on inflammatory conditions. Pharmacologically, NSAIDs inhibit prostaglandins which are synthesized from arachidonic acid by blocking cyxlooxygenase-1 and 2 enzymes. Prostaglandins are known to be overexpressed on inflammatory, premalignant and malignant conditions. The prostaglandins promote tumour development by enhancing tumour cells proliferation, tumour angiogenesis, and tumour cell metastatic opportunity, and by inducing antiapoptotic gene expression. Epidemiological and biomedically, there is significant evidence that NSAIDs could inhibit tumour development. NSAIDs inhibit expression transcription factors, angiogenic factors of tumour angiogenesus, tumour metastasis and depresse expression of antiapoptotic genes. The avidence suggest that potentially NSAIDs could prevent tumour development, besides being analgetic-antiinflammatory drugs.