Colon cancer. Endoscope view of an adenocarcinoma (pink, upper centre) on the inside wall of the colon (large intestine). An adenocarcinoma is a tumour arising from the cells lining the affected organ. Cancer of the colon is common in the developed world, and may be linked to diet. Eating high fat and low fibre foods is thought to raise the risk of developing colon cancer. Symptoms include either constipation or diarrhoea, blood in the faeces and abdominal pain. If the cancer is detected early, surgical removal of the affected portion of the intestine may effect a cure.