Globally, colorectal cancer also called colon cancer or bowel cancer is the third leading cause of cancer. The frequency of colorectal cancer varies around the world; it is common in the Western world and rare in Asia and Africa. In countries where people have adopted the western diets has an increasing incidence of colon cancer.

The colon also known as the large bowel is the longest portion of the large intestine. The large intestine is the last part of the digestive tract, which is a tube that is about five to six feet in length; the first five feet make up the colon which then connects to about six inches of rectum, and finally ends with the anus. About three to eight hours after eating, by the time the food reaches the colon, the nutrients have been absorbed and the remainder is liquid waste product. The colon functions as a converter, changing this liquid waste into stool. The stool can spend anywhere from ten hours to several days in the colon before being expelled through the anus. It has been advised but not proven, that the longer the stool stays in the colon, the higher the risk of colon cancer.

Colon cancer includes cancerous growths in the colon, rectum and appendix. Many colon cancers are thought to arise from adenomatous polyps in the colon. These mushroom-like growths are usually benign, but some may develop into cancer over time. This process can take years which allow time for early detection with screening tests.

Symptoms

Symptoms of the disease are numerous and non-specific. They include fatigue, weakness, shortness of breath, change in bowel habits, narrow stools, diarrhea or constipation, red or dark blood in stool, weight loss, abdominal pain, cramps, or bloating. Other conditions such as irritable bowel syndrome (spastic colon), ulcerative colitis, Crohn's disease, diverticulosis, and peptic ulcer disease can have symptoms that mimic colorectal cancer. Most often, these symptoms are not due to cancer, other problems can cause the same symptoms, so checking with your doctor should be done immediately to be diagnosed and treated as early as possible.

The risk of the cancer rises substantially after the age of fifty, but every year there are numerous cases reported in younger people. Individuals with a personal or family history of , polyps, or inherited syndromes (i.e., FAP and HNPCC), as well as patients with ulcerative colitis or Crohn's disease, are all at higher risk and may require screening at an earlier age than the general population. A person with one first degree relative (parent, sibling or child) with colon cancer is two to three times as likely to develop the cancer as someone who does not have an affected relative.

The treatment depends on the staging of the cancer. When colon cancer is caught at early stages (with little spread) it can be curable. However when it is detected at later stages (when distant metastases are present) it is less likely to be curable. Surgery remains the primary treatment while chemotherapy and/or radiotherapy may be recommended depending on the individual patient's staging and other medical factors.