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Colon cancer,
also called colorectal cancer or bowel cancer, is cancer of the large intestine (colon.) Rectal cancer is cancer of the last several inches of the colon. It is the fourth most common form of cancer in the United States. Most cases of colon cancer begin as small, benign clumps of cells called “adenomatous polyps” in the colon. Usually these growths are benign, but some can develop into cancer over time. Colon cancer is usually diagnosed through a test called a colonoscopy. If the cancer is caught early and confined within the wall of the colon (Stage I and II) it is almost always curable with surgery. If it has spread to regional lymph nodes (Stage III,) then up to 73% are curable with surgery and chemotherapy. If colon cancer has metastasized to distant sites (Stage IV), it is usually not curable, although chemotherapy can extend survival. In some cases of Stage IV colon cancer, a combination of surgery and chemotherapy has seen a patient through to a cure. Radiation is generally used to treat rectal cancer.
Symptoms of colon cancer depend on the location of the tumor in the bowel and whether it has spread anywhere else in the body. Some of these symptoms may occur in other diseases, as well, so none of these symptoms are a direct diagnosis of colorectal cancer. Also, many cases of colon cancer have no symptoms. The following symptoms, however, may indicate colon cancer:
Abdominal pain and tenderness in the lower abdomen
Blood in the stool
Diarrhea, constipation, or other change in bowel habits
Intestinal obstruction
Narrow stools
Unexplained anemia
Weight loss with no known reason
Fatigue
In rectal cancer, symptoms may be more localized, that is there may be a change in bowel habit (constipation or diarrhea,) reduction in the diameter of stool, and a feeling of incomplete defecation. A tumor further up in the bowel is usually characterized by constipation, abdominal pain and vomiting. If a tumor has caused chronic bleeding, iron deficiency anemia may occur. This anemia may cause fatigue, palpitations and pallor (pale appearance of the skin.) Colon cancer may also lead to weight loss, due to decreased appetite.
Risks for colon cancer include:
Being older than age 60
African American and eastern European descent
A diet high in red meat or highly processed foods
Cancer elsewhere in the body
A history of colorectal polyps
Inflammatory bowel disease (Crohn's disease or ulcerative colitis)
A family history of colon cancer
A personal history of breast cancer
Smoking
Excessive consumption of alcohol
Certain genetic syndromes also increase the risk of developing colon cancer. Two of the most common are hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, and familial adenomatous polyposis (FAP).
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