Study on Aspirin Versus Placebo in Resected Colon Cancer With PI3K Mutation Stage III or II High Risk

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