Adjuvant Aspirin Treatment for Colon Cancer Patients

Following complete resection of their primary tumor, potentially eligible stage II or stage III colon cancer patients will undergo central PIK3CA testing. Patients with somatic mutations will be 2:1 randomized to daily aspirin 100 mg versus placebo for a a maximum of 3 years or until disease recurrence, patient death or withdrawal of consent, whichever occurs first. Patients will be followed up for at least 3 years from the date of surgery. The intake of aspirin or placebo is independent of adjuvant chemotherapy, and does not impact on the indication to give (or not to give) adjuvant chemotherapy.

Colorectal cancer is the third most common malignancy for both women and men and is responsible for almost 10% of all cancer death. Despite complete removal of the tumor and use of adjuvant chemotherapy, up to 25% of patients with stage II colon cancer and up to 50% of patients with stage III disease will suffer from recurrences, which is associated with poor prognosis. Several retrospective observations have documented a favorable effect of long-term intake of oral aspirin for the prevention of colorectal cancer in different clinical situations. Regular intake of aspirin after the diagnosis of colorectal cancer may also be associated with a lower risk of colorectal cancer-specific and overall mortality. Two recent publications in prestigious medical journals provided retrospective evidence that patients with PIK3CA-mutated colon cancer may derive a very substantial benefit from daily oral aspirin. Both analyses showed a roughly 85% reduction of the risk for tumor relapse compared to patients who did not take aspirin. However, a potential selection bias in these retrospective analyses cannot be excluded with certainty. These extremely interesting and intriguing findings must be confirmed in a randomized controlled trial to potentially change clinical practice. The trial objective is to demonstrate a statistically significant and clinically relevant disease-free survival benefit in stage II and III PIK3CA mutated colon cancer patients taking daily adjuvant aspirin for 3 years. Patients with resected colon cancer stage II or stage III bearing somatic mutations in exon 9 or 20 of PIK3CA will be 2:1 randomized to daily adjuvant aspirin 100 mg versus placebo for a maximum of 3 years or until disease recurrence, patient death or withdrawal of consent, whichever occurs first. Patients will be followed up for at least 3 years from the date of surgery. The intake of aspirin or placebo is independent of adjuvant chemotherapy, and does not impact on the indication to give (or not to give) adjuvant chemotherapy.