Cancer of the Colon And Rectum

The large bowel consists of the colon and the rectum through which solid and semi-solid waste is passed. The colon is about 150 cm (5 ft) long and the rectum occupies about the last 15 cm (6 in) of it.

Symptoms

There are several early signs of colonic or rectal cancer but the main one is blood in the stools which can be bright red, dark red or black in colour. Other symptoms are a change in bowel habits such as diarrhoea or constipation and occasionally abdominal discomfort or pain.

Diagnosis

A tumour in the rectum is within the reach of a doctor’s examining finger and will therefore be found by rectal examination. To confirm this the tumour can be viewed by means of a proctosigmoidoscope through which it is possible to see the lower twelve inches of the bowel where many tumours of the large bowel occur. A sample of tissue (biopsy) which is taken for examination under a microscope will confirm the diagnosis. This can also be confirmed by introducing a contrast medium (barium enema) into the bowel and taking a series of X-rays which may reveal an obstruction. In another test, a search is made for hidden blood in the stools; this is analysed in the laboratory. More recently, the fibre-optic colonscope, a highly flexible tube no thicker than a finger which can be moved through the curves and around the bends of the colon, has made the examination of the entire bowel possible.

Treatment

Cancer of the colon sometimes starts with a small cherry-like polyp suspended on the intestinal wall. This is easily removed through the colonoscope and if proved malignant more extensive surgery will be required. Sometimes it will be necessary to perform a colostomy, which means an opening of the bowel through the skin surface of the abdomen to allow body waste to be removed. The colostomy may be either a temporary or a permanent one. The temporary one is usually carried out to permit the bowel to rest during the time required for healing. If a large part of the colon including the rectum has to be removed the colostomy will be a permanent one and the patient will need to wear a colostomy bag. At first, this is repugnant to many patients but eventually, with patience, most people become accustomed to managing their lives without being too upset by having to dispose of their soiled plastic colostomy bags.

Sometimes radiotherapy is used instead of surgery and at other times it can be used before an operation to help shrink the tumour. This makes the operation much safer. Occasionally a course of X-ray treatment is recommended as a follow-up to surgery, especially when the rectum has been removed. Finally, in advanced cases when surgery is not possible, palliative radiotherapy is an effective means of relieving pain due to the growth.

Chemotherapy will have to await the discovery of new drugs before it can be used more extensively in the treatment of advanced bowel cancer.