Patients will be followed up with 3 monthly assessments in the first two years and 6 monthly assessments in the rest three years. Stratification factors include age , BMI , gender , tumor location , rectal or colon cancer stage,the chemotherapy (FOLFOX, XELOX, DeGramont or Capecitabine ),laparoscopic or laprotomy, anastomosis, concomitant medications and complications.