What is colon cancer?
Colon cancer is cancer of the large intestine, also known as the colon. If the last segment of the colon, the rectum, has a cancerous growth, it is known as rectal carcinoma. These two conditions are collectively referred to as colorectal cancer.
Carcinoma of the colon is the most common malignancy after the age of 50 years, and its incidence doubles with each successive decade. The incidence of colon cancer is especially high in the Western world.
The word “cancer” itself is frightening to all of us. However, colon cancer is easily curable if it is caught in the early stages of its growth.
Am I at risk of developing colon cancer?
There are certain conditions which predispose you to developing colon cancer. These are broadly known as "pre-cancerous" conditions. The pre-cancerous conditions of the colon include:
Certain environmental and genetic factors favor the development of colon polyps. The chance of a polyp becoming malignant is increased when the polyp is more than 1 cm in size, multiple, or flat in shape. A common autosomal dominant condition known as "familial adenomatous polyposis" has a 100% chance of transforming into malignant cancer if left untreated. It is a reasonably common condition occurring in 1:30000 people, and is usually passed down genetically from one or both parents. In patients with familial adenomatous polyposis, polyps begin to develop in the colon during the teenage years; later in life, these polyps lead to the development of colon cancer.
Inflammatory Bowel Disease
Chronic inflammatory bowel disease refers to two conditions; these are "ulcerative colitis" and "Crohn’s disease." Exposure to large amounts of radiation can also increase the incidence of inflammatory bowel disease.
Ulcerative colitis is a disorder in which the mucosa and submucosa of the colon become inflamed. Men are slightly more likely than women to be affected by ulcerative colitis. It is a definite pre-cancerous condition. If dysplastic changes (abnormal growths) are seen during a colonoscopic biopsy, it is presumed that the affected area will soon transform into a malignant growth. In these cases, a colectomy (removal of part or all of the colon) is performed.
Crohn’s disease is a disorder in which inflammation affects all layers of the colon (not just the mucosa and the submucosa), and may involve any or all parts of the gastrointestinal tract, from mouth to anus. Crohn’s disease is frequently diagnosed in late adolescence or early adulthood and affects mostly women. The risk of developing colon cancer from Crohn's disease is less than with ulcerative colitis.