Colon cancer is a type of cancer that develops in the colon, which is the main part of the large intestine. It usually begins in the inner lining of the colon and often develops from precancerous growths called polyps. Common symptoms include blood in the stool, persistent changes in bowel habits, abdominal pain, unexplained weight loss, fatigue and iron-deficiency anaemia. Risk factors include increasing age, family history of colorectal cancer, obesity, physical inactivity, smoking, alcohol consumption and diets high in processed meat. Colon cancer is diagnosed through investigations such as colonoscopy, biopsy and imaging.