Left-sided colonic carcinoma is characterised by a change in bowel habit due to obstruction. Pain is felt in the left side of the abdomen because there is commonly involvement of the sigmoid colon and the rectosigmoid junction, and there is gross blood in the stool. The carcinoma tend to be small, annular and ulcerated. It appears as a fixed filling defect with an annular "apple core" configuration on barium enema. Usually, the patient is over 40 and commonly, over 70 years of age. Men are affected slightly more than women.