COLORECTAL CANCER

What Is Colorectal Cancer? Cancer occurs when abnormal (malignant) cells in an organ or tissue grow in an uncontrolled manner forming a mass known as a tumour. Cancer cells are called malignant because they can invade and destroy normal tissue around them and spread (metastasize) to other organs. In contrast, benign tumours are accumulations of cells that grow abnormally, but do not spread. In colorectal cancer, malignant cells arise and grow in the colon or rectum, which together make up the large intestine. Colorectal cancer is a highly treatable and often curable disease if discovered in its early stages when it is still localized in the bowel. Most colorectal tumours start from adenomatous polyps, small benign gland-like growths that occur in the inner lining of the large intestine. The progression of cancer from most types of polyps takes about five to ten years. However, inherited forms of polyps may progress much faster than this and start at a younger age (15-20 years old). Screening for colorectal cancer (see under Tests, below) should be a part of routine care for all adults starting at age 50 years, especially for those who have first-degree relatives with colorectal cancer.

What Causes Colorectal Cancer? Defects in genes that normally protect against cancer play a major role in causing polyps to grow uncontrollably and become cancerous. There are two main genetic conditions that lead to colorectal cancer: familial adenomatous polyposis and hereditary non-polyposis colon cancer. Along with genetic factors, there is a strong environmental association with the development of colorectal cancer. Numerous studies have suggested that diets high in fat, protein, calories, alcohol, and meat (both red and white) and low in calcium and folate are associated with an increased incidence of colorectal cancer. Cigarette smoking is also a significant risk factor.

What Are The Signs And Symptoms Of Colorectal Cancer? Because colorectal cancer is treatable if found early, it is important to be aware of any of the following signs, which may indicate cancer: changes in bowel habits (diarrhea or constipation), blood in the stool, stools that are abnormally small in width, abdominal discomfort (bloating, fullness, cramps), frequent gas pains, constant feeling of having to go to the bathroom, unexplained weight loss, and any signs of anemia (weakness, fatigue, heart, palpitations, shortness of breath, and exercise intolerance). One very important point in helping to obtain a favorable treatment outcome is to consult a physician immediately if you have any of the signs and symptoms of colorectal cancer mentioned above. In particular, do not self-diagnose the presence of blood in the stool that lasts more than two weeks as hemorrhoids - instead, see your doctor!

With What Can Colorectal Cancer Be Confused? There are many causes of blood in the stool other than colorectal cancer. These include diverticular disease, inflammatory bowel disease, ischemic colitis (infectious colitis, radiation colitits), benign colonic polyps, lymphoma of the large bowel, hemorrhoids, anal fissure, trauma, foreign body and rectal ulcers. It is important for your doctor to make sure that a change in color of the stool is truly due to blood, since eating certain foods such as beets or red licorice and taking certain medications such as iron supplements and Pepto-Bismol can change the color of the stool.

Tests that help to distinguish colorectal cancer from the above conditions include the following: (1) detection of the presence of blood in the stool (so called fecal occult blood test); (2) sigmoidoscopy (a procedure in which the inside of the rectum and of the left descending colon are visualized by using an instrument known as a sigmoidoscope); (3) barium enema X-ray examination; and (4) colonoscopy. The latter is the most definitive test and is thus often referred to as the gold standard; it can detect tumours that are not picked up by other tests.

What Can You Do To Prevent Colon Cancer? There are several ways to reduce your risk of colon cancer. Dietary changes include decreasing fat intake (less than 30% of your calories), and increasing your intake of fiber (20-30 grams a day), calcium and folate. Lifestyle changes include regular exercise and stopping smoking. Recent evidence has indicated that non-steroidal anti-inflammatory drugs such as aspirin, may prevent formation of adenomatous polyps or cause them to regress. However, you should discuss all of these recommendations with your doctor before attempting any of them.

How Is Colorectal Cancer Treated? The three most common treatments of colon cancer are surgery, radiation therapy, and chemotherapy. The first line of treatment is surgery or surgery followed by chemotherapy and radiation. Surgery often involves removing the section of the bowel where the cancer is found, and also the adjacent lymph nodes. Sometimes the large bowel has to be opened onto the surface of the abdominal wall (a colostomy). Some patients may also receive an initial treatment of chemotherapy and/or radiation therapy in order to shrink the tumour before surgery.