Colon cancer. X-ray of the colon of a 59 year old patient with cancer of the sigmoid colon. The patient was given a barium enema prior to the X- ray to show up any abnormalities. The irregular filling of the colon with the barium (white) shows the presence of a tumour. The sigmoid colon is at the end of the small intestine and start of the colon. Symptoms of colon cancer include rectal bleeding and abdominal pain. Treatment is with surgery to remove the affected area. Colon cancer is one of the most common cancers in the Western world. It is a disease of late and middle age. Risk factors include a diet high in animal fat and low in fibre and a sedentary lifestyle.