Colon cancer. Gross specimen of an adenocarcinoma (growth at centre left) in tissue from the caecum, the first part of the colon (large intestine). An adenocarcinoma is cancer of the glandular linings found in many different organs, including the wall of the digestive tract. Colon cancer is one of the most common cancers in North America and Western Europe. It is thought to be connected to following a diet high in fat and low in fibre. The cancerous part of the colon is surgically removed, followed by chemotherapy and radiotherapy if the cancer has spread.