Large bowel forms lower 1.5 metre part of the gastrointestinal tract, going up from the right lower abdomen as ascending colon, then horizontally as transverse colon, coming down on the left side as descending colon and then as rectum ending at the anus.
Cancers of the colon and rectum are not common in India. But they arc one of the most common sites of cancer in the USA, Denmark and some other European countries. In the USA nearly 45,000 people die of this cancer.
Causes
Those people who pass stool daily or even oftener because of having more roughage in the diet, have less of cancer of the large bowel. Those who form and pass less stool because their diet contains no roughage, have a higher incidence of colon cancer. This might be due either to the longer staying in of the cancer-causing diet, or the production of bacteria due to putrefaction of faecal matter which may be carcinogenic.
Symptoms
· Constipation or diarrhoea alternating with each other.
· Pain in the lower abdomen.
· Blood in the stool.
· Early fatigue.
· Loss of weight.
Diagnosis
· Routine: Blood: Hb, RBC, TLC, DLC may be normal. ESR may be raised. Stool shows blood in it
· Special: Sigmoidoscopy and biopsy examination or colonoscopy and biopsy, confirm the diagnosis.
· Additional: Ultrasound scan of the liver for secondaries. X-ray of the chest for secondaries.
Treatment
Surgery: Chances of removal of the cancerous part are good with surgery, depending upon the extent to which the cancer has spread. If it is confined to the inner lining of the colon (stage I), the chances of cure are excellent If it has spread in the muscular wall of the colon, the chances are fair. But if the cancer has spread into the lymph glands draining from the area of cancer, then even in spite of the removal of the involved lymph glands, the chances of cure are diminished.
If the cancer involves the rectum then after removal of the involved part, instead of connecting the normal colon with the anus, the surgeon opens the end of the normal colon on to the abdomen. The faecal matter collects in a bag tied over the opening and is removed and cleaned periodically. This procedure is called colostomy. It is inconvenient but the patient gets used to it.
Radiation: If the cancer is in the sigmoid colon or the rectum and gone on to stage II or HI, then radiation before or after surgery, is helpful, in lessening the chances of relapse.
Chemotherapy: About 20 per cent of the patients respond to 5-Fluorouracil. The drug does not cause much of side-effects.
This drug is also used if secondaries of the cancer have developed in other parts of the body.
Early Detection
Signs & Symptoms
· Constipation or diarrhoea alternating with each other.
· Pain in the lower abdomen.
· Passing blood in the stool.
· Loss of weight.
Investigations
· Sigmoidoscopy and biopsy examination
· Colonoscopy and biopsy examination