The colon is the large intestine. It begins where the small intestine ends, near the appendix inside the right lower abdomen. The colon extends in a wide loop, up the right side of the abdomen to the liver, and across to the left side of the abdomen where it turns down connecting finally to the rectum. Its main function is to solidify stool by reabsorbing much of the water from the liquid stool that enters it. And, of course, it stores formed stool until it can be evacuated through the rectum.
Polyps and Cancer
Polyps are growths that form on the inside lining of the colon. They are usually shaped like mushrooms or dome-like buttons, and vary in size from a tiny pea to larger than a plum. While colon polyps start out as benign tumors, certain types of polyps (called an adenoma or adenomatous polyp) may turn into cancer. The risk is greater as the polyp gets larger. However, polyps are rather slow growing. It may take five years or more for a polyp to reach 1/2 inch in size. If an adenomatous polyp does turn into cancer, it may take an additional five to ten years, or more, to reach that stage.
Colon cancer is very common, occurring in over 150,000 people in the United States each year. More than 90% of the patients can be cured if the cancer is detected and removed at an early stage. Adenomatous polyps can be removed before they become cancerous with a procedure called colonoscopy. A lighted flexible tube is inserted into the colon, allowing the physician to see the inside of the colon. Various accessories can be passed through the tube to remove any polyps that may have formed. This procedure is usually done in an outpatient setting and under light sedation.
Causes and Risks
The complete cause of polyp formation and colon cancer is unknown, but it is known that heredity plays a key role. Certain genes seem to prevent colon cancer from developing. Some people may lose these protective genes. This genetic deficiency can be inherited. A person whose parents, brothers or sisters have colon cancer is at significantly greater risk of developing it. There is also risk (but to a lesser degree) if uncles, aunts and grandparents have had the disease. Therefore, everyone with a family history of polyps and colon cancer should be evaluated by their physician and examined regularly.
Lifestyle and some medical conditions can increase the odds of developing colon polyps and cancer. A low fiber diet appears to contribute to the development of colon cancer. The rate of colon cancer increases in people after the age of fifty, as well as in people who have ulcerative colitis for a long period of time. Also, females who have had genital or breast cancer are at increased risk of developing colon, cancer.
Diet seems to be important in preventing colon cancer. Rural residents in Africa and India rarely develop colon polyps or cancer. Their diets are high in unprocessed grains (the bran or fiber is not removed) and low in meat. However, when these people move to westernized societies and adopt the typical western diet, over time they develop the same incidence of colon polyps and cancer. It appears that adopting a diet with less meat and at least 20 to 30 grams of fiber a day could play an important role in reducing the risk of developing polyps and colon cancer.
Meat - used in excess in the diet may be harmful. The fat, when broken down by the body's digestive juices, may change into compounds called carcinogens. These molecules are known to cause colon cancer in some animals. Diets high in fiber and roughage produce bulky stools. It is likely that large, bulky stools help to sweep the colon of carcinogens.
Fiber - the indigestible part of plants. Insoluble fiber does not dissolve in water. It adds bulk to the stool and regulates movement of the stool through the bowel. Wheat bran is a good source of insoluble fiber. Soluble fiber absorbs great quantities of water, and becomes gelatinous. It is known to reduce blood cholesterol. Soluble fiber is found in such foods as oats, barley, brown rice, legumes, apples, strawberries and carrots. There are also stool bulking agents available in drugstores which contain a soluble fiber called psyllium mucilloid, from a plant commonly grown in India. These products go by trade names such as Metamucil and Konsyl. There are also generic forms available. They are useful in treating irregularity, some diseases involving the intestinal tract (such as irritable bowel syndrome and diverticulosis), and perhaps in preventing polyps and colon cancer.
If there is a problem getting enough fiber in the diet, use the following recipe for a low-calorie fiber supplement. Buy miller's wheat bran from a health food store and a Nutrasweet psyllium mucilloid product from the drugstore. Take a heaping tablespoon of each in 6 to 8 oz of water or juice, once or twice a day. This formula contains 20 grams of soluble and insoluble fiber.
Calcium - one of the most common minerals in the body. It is necessary for bone strength and for many of the body's important chemical processes. For example, it is needed in regulating the growth of cells. Animal studies have found that a lack of calcium leads to excessive cell growth in the colon. It is not clear if calcium has a cancer preventive benefit for humans. Still, since it is important to the body in so many other ways, everyone should get enough calcium in the diet. All adults should have 1000 mg per day. After menopause, females have a greater risk of osteoporosis (loss of calcium causing bones to weaken), and they should have 1500 mg of calcium a day.
A quart of milk a day does a good job of providing adequate calcium. Most people do not drink a quart of milk everyday, but there are other sources of calcium. Remember that some foods, such as puddings and custards, are prepared with milk. All dairy products (such as cheeses and yogurt), shellfish, seafood and many leafy green vegetables also contain calcium. However, the calcium in leafy vegetables is not as available for use by the body as calcium in milk. Some people on low calorie or special diets may not be able to get enough calcium in their diets. In these cases, the physician can recommend a calcium supplement. Calcium carbonate or calcium citrate are the best because they provide the most available calcium.
Aspirin - a miraculous drug. It relieves pain and fever and is good for heart patients because it thins the blood. Now, medical studies show that the incidence of cancer of the esophagus, stomach, colon and rectum are less in those people who take aspirin regularly. It is known that prostaglandin (a hormone-like substance produced by the body) may promote excessive or abnormal cell growth in the intestine. Aspirin appears to interfere with prostaglandin, which may account for its role in preventing colon cancer.
How much aspirin is enough? A regular adult aspirin contains 325 mg. The effective dose for blood thinning or colon cancer prevention is probably in the range of 150 mg a day. One children's aspirin contains 80 mg. Some manufacturers are now making low dose aspirin. There is one caution; aspirin can cause stomach ulcers or even serious bleeding. Therefore, even in low doses, it should only be taken with the approval of a physician.
Each person is unique and should be evaluated by a physician for the treatment of any medical condition or disease. In general, however, the following are important actions to follow in preventing the development of colon polyps and cancer,
1. Fiber - 20 to 30 grams a day in the diet and/or as supplements.
2. Calcium - 1,000 to 1,500 mg of dietary calcium and/or as supplements.
3. Aspirin - probably once a day.
4. Colonoscopy - for those with close relatives who have had colon polyps or cancer.
5. Colon polyp removal - to prevent these polyps from becoming cancer.