The recent observation [40] that the improvements in cancer and overall mortality seen in two large prospective cohorts associated with aspirin use after a diagnosis of colorectal cancer correlate with the presence of mutated PIK3CA within the tumour provides further insights into the possible anti-cancer mechanisms of aspirin, as well as raising the possibility that molecular profiling may be able to select patients most likely to respond to aspirin. The gene discussed is PIK3CA; the disease is cancer.