What is colon cancer? Colon cancer is cancer of the colon or large intestine. Rectal cancer is cancer in the last few centimeters of the colon. Together, they are often called colorectal cancers. Most cases of colon cancer start as small, harmless clumps of cells called polyps. Over time, some of these abnormal growths can become colon cancers. Polyps may be small and produce few signs of disease. For this reason, doctors recommend regular screening tests to help prevent colon cancer. SymptomsSome symptoms of colon cancer are changes in your bowel habits, including diarrhea or constipation, rectal bleeding or blood in the stool, constant abdominal discomfort, such as cramps, gas. or pain, a feeling that your bowel is not emptying completely, weakness or fatigue, and/or unexplained weight loss. Many people with colon cancer have no signs of illness in the early stages of the disease. When signs of disease appear, they likely differ depending on the size of the cancer and its location in the large intestine. If you notice any of these signs of colon cancer, such as blood in your stool, make an appointment with your doctor. Talk to your doctor about when you should start colon cancer screening. Guidelines generally recommend that colon cancer screening begin at age 50. Many doctors recommend more frequent or earlier screening if you have other risk factors, such as a family history of the disease. Causes In most cases, the cause of colon cancer is not clear. Doctors know that colon cancer occurs when healthy cells in the colon become changed. Healthy cells grow and divide in ways that keep your body functioning properly. But when a cell is damaged and becomes cancerous, the cells continue to divide, even if new cells do not... middle of paper ...... is a common component of rectal cancer treatment, especially if the cancer has broken through the wall of the rectum or spread to nearby lymph nodes. Radiotherapy, normally combined with chemotherapy, can be used after surgery to reduce the risk of the cancer coming back to the rectum where it started. Prevention To prevent new cancers from developing, scientists examine risk factors and protective agents. Anything that increases your risk of developing cancer is called a cancer risk factor; anything that reduces your risk of developing cancer is called a cancer protective factor. Some cancer risk factors can be avoided, but many cannot. For example, smoking and inheriting certain genes are risk factors for certain types of cancer, but only smoking can be avoided. Normal excise duties and a healthy diet can help reduce risks, but promise nothing..