COLORECTAL CANCER

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Who are in the early symptoms and signs of colorectal cancer?

The colorectum is a hollow muscular tube concerned with allowing digested food and waste to pass through. Symptoms therefore only arise when this smooth passage is disturbed, and because of the elasticity and huge reserve of the large intestine, symptoms are often minimal or occur only late in the disease. Hence, 60% of colorectal cancer patients presenting to hospitals already have lymph node spread or widespread cancer. Symptoms depend on the stage of the disease as well as the location of the cancer In the colorectum. During the early stages of cancer most patients do not have symptoms. The commonest symptom of large bowel cancer is rectal bleeding which occurs in both benign adenomas and cancers. Often however this can only be detected in very minute amounts and cannot be seen with the naked eyes.

As a summary the following may be useful:

1. Blood in the stools. 2. A change from your normal bowel habit usually with looser stools with no immediately obvious reason. 3. Unexplained loss of weight. 4. Recent onset of abdominal colic. 5. A persistent feeling of still having stools in spite of last having had a bowel motion.

What sort of tests might the doctor do on me?

Generally the hospital doctor will take a detailed account of your medical problems as well as making you relate your past and family history. The doctor will then do a physical examination that must include a rectal examination and a proctoscopy. You may then be asked to do a faecal occult blood test, a blood test as well as be booked for colonoscopy or a barium enema test. If cancer is already confirmed, liver ultrasound or CAT scan may be needed.

Is the carcino-embryonic antigen (CEA) an useful test?

The carcino-embryonic antigen (CEA) is a protein that is easily measured with an inexpensive and simple test. CEA is normally found in low concentrations in embryonic and fetal gut as well as in pancreatic, lung and liver cells. Hence mild elevations may be found in pregnancy, as well as in smokers and in inflammatory and as well as malignant conditions of the respiratory, hepato-biliary and gastrointestinal system.

This test is not done for screening, as it is only helpful after a diagnosis of colorectal cancer is made. However, a raised CEA in a "normal" person must be an indication that the colorectum needs to be investigated further.

What sort of investigative methods are there to examine the
large intensine?

i. Barium enema

This is a special x-ray procedure where dye (barium sulfate) and air is pumped through the anus to visualize the large bowel. Although it is not as accurate as colonoscopy, it can pick up most large polyps and cancers and is several times cheaper than a colonoscopy. One disadvantage is the inability for simultaneous excision of polyps as biopsy is not possible. For a few days following the test your stools may be whitish but there is nothing to be concerned about as it is only the barium which is being passed out.

ii. Colonoscopy

This is the gold standard for detection of colonic lesions. For this test to be successful, the large bowel has to be meticulously cleaned before the procedure. Most modern laxatives work with the ingestion of two or three liters of plain water and should produce about 2 to 6 loose watery diarrhoea starting within an hour after ingestion of the laxative. A sedative may be given but most patients undergoing colonoscopy have very mild tolerable discomfort and do not require sedatives. In any case the unsedated patient may be guided through the procedure and any lesions found may be pointed out to you and may help you to understand your situation better. The lack of availability of colonoscopy for everyone; the expense and the small risks involved should not mitigate against those who would prefer a total colonoscopy as a screening test for the detection of colorectal cancer and its precursor polyps. Thus people who have the means and the resources and who understand the risks involved should certainly be allowed to avail themselves to this method of investigation.

iii. New imaging modalities

New modalities like capsule colonoscopy, virtual colonoscopy a colonoscopy are being investigated and may be offered by limited new centers on an experimental basis. Virtual colonoscopy is a diagnosis on and the presence of polyps, meaning that a real colonoscopy will have performed to remove the said lesion.

What are the different stages of colorectal cancer?

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