COLORECTAL CANCER

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What is a Colorectal Cancer?

Every living tissue and organ in the body is made up of tiny building blocks called cells. Normal cells in the body grow at a steady and controlled rate. New cells are normally formed to replace worn out cells or to repair injured cells. Occasionally some of these cells proliferate out of control and have the tendency and ability to spread in an abnormal way to other organs and tissues These cells hence use up the body reserves as well as destroy bodily function.

These abnormal cells are called cancer and the growth is an abnormal and uncontrolled group of cells. Cancer thus results in severe general malnutrition and malfunction of affected organs. Moreover cancer cells have the ability to spread beyond the original site of cancer growth Malignant tumors or cancers do not just grow large at the original site of cancer growth. Malignant tumors (also called primary cancer) but their cells can also travel to other organs and form secondary tumors.

These secondary growths are called metastasis and the ability to form such a metastasis is the hallmark of a malignant cancer. Colorectal cancer arises from the innermost lining of the wall of the colon and rectum. This epithelia llining is also called the mucosa layer of the large intestine.

What are the possible protections against colorectal cancer?

Low dose (80 mg) aspirin has been reported to reduce the chance of recurrent adenomas of the large intestine after pre-existing polyps have been removed by 19% In patients with advanced adenomas or colorectal cancer, the risk of adenoma or cancer recurrence was also reduced by 40%. However a higher dose is not more protective but actually had a lesser effect, reducing adenoma recurrence overall by 4% and advanced adenoma and colorectal cancer recurrence by 19% only.

Many studies have shown that non-steroidal anti-inflammatory drugs (NSAID) such as aspirin and others can reduce the size and number of polyps in patients with familial adenomatous polyposis. These drugs however cause a lot of gastric upset and ulceration. More recently a new class of NSAID known as COX-2 inhibitors have been tested and preliminary results were said to be efficacious without the gastric side effects. These drugs are currently undergoing further testing.

The most useful and fail safe method currently of preventing colorectal cancer however, is colonoscopy and removal of all pre-malignant polyps present. Regular exercise is important in maintaining a healthy Removal of a large polyp lifestyle and may help in the prevention of colorectal cancer. Brisk activity three to five times a week including walking, cycling, swimming, aerobic exercises or jogging will certainly help maintain general good health and boosts the body's immune defense against infection and cancer. Certain environmental factors including diet high in fat, excessive caloric and alcohol intake, obesity, sedentary life style and smoking have an association with increased risk of colorectal cancer and a change in lifestyle may be of some value in preventing colorectal cancer.

Who are in the high risk groups for large bowel cancer?

People with high risks of colorectal cancer includes those with :

1. a strong family history of large bowel cancer or other related cancers in first degree relatives. 2. a previous history of adenomas or cancer of the large bowel. 3. a history of chronic ulcerative colitis or Crohn's disease.

One of the most important factors in the pathogenesis of large bowel cancers may be inherited susceptibility for colorectal cancer. First degree relatives of patients with colorectal cancer have therefore increased risk of about 3-4 times for development of colorectal cancer compared to the average person in the street. Patients with a previous colorectal cancer have also a 3-4 times increased risk of developing a second large bowel cancer and therefore life long surveillance in these patients is essential.

Patients with adenomas and especially those with familial adenomatous polyposis (a genetic condition where hundreds or thousands of adenomas may be present), are at increased risk of cancer formation unless polyps are removed totally. Patients with ulcerative colitis and Crohn's disease have increased risk for developing large bowel cancer especially if the disease has been present for more than 10 years.

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