Four retrospective studies were recently published on efficacy of aspirin in patients with surgically resected colon cancer. Two of these studies strongly suggested that aspirin used in low doses (100 mg/d) after surgical resection of colorectal cancer with PI3K mutation could act as a targeted therapy with a major protective effect on the risk of recurrence. The other two studies did not confirm the benefit of aspirin in this situation. These four retrospective studies provide an insufficient level of evidence to demonstrate the benefit of low-dose aspirin as adjuvant to surgery for colorectal cancer. Therefore, it is necessary as recommended in the conclusion of these studies and meta-analyses to perform a randomised prospective study to validate these data.

Inclusion Criteria:

• Age ≥ 18 years

• Colonic adenocarcinoma stage III

• Colonic adenocarcinoma stage II high risk MSS:

  • T4bN0 or T4aN0 tumour penetrating the surface of the visceral peritoneum
  • or less than 12 nodes evaluated;
  • or with at least two of the following criteria:lymphatic involvement, perineural invasion, venous invasion
  • or diagnosis of bowel obstruction or perforation; or poor differentiated tumour.

• PI3K mutation, exon 9 or 20 (tumour)

• Resection R0

• WHO performance status 0-2

• Chest and abdominal CT scan ≤ 8 weeks

• Life expectancy ≥ 3 years

• Written consent signed

Exclusion Criteria:

• Anticoagulant and/or Antiaggregating treatment including clopidogrel
• Regular aspirin use (> 3 doses per week during more than 3 months the last year)
• Contraindication to Aspirin : Allergy to aspirin, Active or antecedent peptic ulcer
• Severe renal or hepatic insufficiency
• Pregnancy or nursing ongoing
• Rectal cancer
• Hereditary forms (i.e. lynch syndrome patients)
• Follow-up of the patient not feasible