Observational studies suggest that aspirin can reduce the risk of colorectal cancer (CRC) recurrence, but randomized trials have not proven this benefit. Now, new data from the phase III ALASCCA trial demonstrate benefit in a biomarker-selected patient population.

Translational research indicates that COX2, a target of aspirin, has a crucial role in PI3K pathway-altered CRCs. Therefore, ALASCCA specifically enrolled patients with resected stage II–III colon cancer or stage I–III rectal cancer harbouring either PIK3CA exon 9 or 20 hotspot mutations (group A; n = 314) or other somatic alterations in PIK3CA, PIK3R1 or PTEN (group B; n = 312). Patients in each group were randomly assigned (1:1) to receive low-dose aspirin (160 mg) or placebo once daily for 3 years, in addition to local investigator-determined, guideline-recommended perioperative therapy. The primary end point was time to CRC recurrence.