PTGS2 and cancer: Furthermore, the intake of aspirin does not seem to confer consistent therapeutic benefits across different cancer types (Table S3).19 Several hypotheses have been suggested, such as the involvement of PIK3CA, which mediates PTGS2 expression, the gene that codes for COX-2.76 COX-2 inhibitors are also known to independently demonstrate potent anti-tumourigenic effects.77,78