cancer of colon

The cancer of colon - A malignant tumour of the colon (the major part of the large intestine). Cancers of the colon or of the rectum (the lower part of the colon), which are generally referred to as colorectal cancer, are among the most common forms of cancer. They most often occur in people over the age of 60.

CAUSES:
A genetic basis has been found for some types of colon cancer. Up to one in three cases are associated with a family history of colon disease. In particular, an inherited disorder called familial adenomatous polyposis (in which large numbers of polyps develop in the colon) greatly increases the risk. In the majority of cases, however, the precise cause is not known. Contributory factors include diet: eating a lot of meat and fatty foods and not enough fibre may increase the risk. The disease also sometimes occurs in association with ulcerative colitis.

SYMPTOMS:
The first symptoms of colon cancer include an inexplicable change in bowel movements (either constipation or diarrhoea), blood mixed in with the faeces, and pain in the lower abdomen. Sometimes, however, there are no symptoms until the tumour has grown large enough to cause an obstruction in the intestine (see intestine, obstruction of) or perforate it (see perforation).

DIAGNOSIS AND TREATMENT:
Successful treatment of cancer of the colon depends, crucially, on an early diagnosis. Screening may be carried out to detect early signs. This procedure includes a test to detect blood hidden in the faeces (see faecal occult blood test). If the test is positive, doctors may perform sigmoidoscopy and colonoscopy to view the inside of the colon. A biopsy may be performed at the same time. In most cases, a partial colectomy is carried out. In this procedure, the diseased part of the colon is removed, together with a surrounding area of healthy tissue, then the cut ends of the colon are rejoined. Surgery may be combined with radiotherapy or possibly with chemotherapy. The chance of survival depends on how far the tumour has spread, but colon cancer in its early stages can be cured.