Phase III, Multi-centre, Double Blind, Randomized Placebo Controlled Trial of Aspirin for Duke C and High Risk Dukes B Colorectal Cancers

INTERVENTION: Intervention1: Aspirin: 200 mg OD for 3 years Control Intervention1: Placebo: 200 mg OD for 3 years CONDITION: Dukes C and High Risk Dukes B Colorectal Cancer PRIMARY OUTCOME: 1. Disease free survival for all eligible subjects (high risk Dukes B colon cancer, Dukes C colon cancer and rectal cancer ptient sub groups)‐‐‐‐‐‐Timepoint: 3 years Disease free survival for colon cancer (high risk Dukes B and Dukes C colon cancer)‐‐‐‐‐‐Timepoint: 3 years SECONDARY OUTCOME: Overall survival over 5 years‐‐‐‐‐‐Timepoint: 5 years INCLUSION CRITERIA: 1. Male or female outpatient of >= 18 years of age 2. Dukes C colon cancer, high risk Dukes B colon cancer, Dukes B rectal cancer or Dukes C rectal cancer 3. Undergone complete resection of primary tumor 4. Completed standard therapy (atleast 3 months of chemotharapy +‐ radiotherapy 5. Within 90 days of completion of standard therapy (syrgery, chemotherapy +‐ radiotherapy) 6. ECOG performance status 0‐2 7. Satisfactory haematological or biochemical functions (tests should be carried out wuthin 2 weeks prior to randomization) 8. Creatinine clearence > 50 ml/min 9. Total bilirubin <= 1.5 x upper limit normal 10. AST/ALT <= 3 x the upper limit nirmal