Over 100,000 Americans are diagnosed with colon cancer each year. Colon and rectal cancer account for 9% of all deaths of men in the U.S. Overall survival rates for the disease are in the neighborhood of 60%. However, the survival rate is much better if the cancer is detected early and much worse if it is detected in an advanced stage.
Function of the Colon
Food is digested in the mouth, stomach, and small intestines. The undigested material moves into the colon, or large intestines, where the body absorbs much of the remaining water, salts (e.g. magnesium, sodium, and chloride) and some vitamins (e.g. vitamin K). Bacteria resident in the colon digest some of the fiber that the body could not digest, providing nourishment to the cells lining the colon. The colon stores the remaining solid waste until it is eliminated as feces.
Colon cancer generally begins as a small non-cancerous growth called a polyp. Not all polyps become cancer, but when they do, the cancer grows until it interferes with normal function of the colon. It can also spread (metastasize) to other parts of the body, like the liver and lungs.
While most victims of colon cancer have no known risk factors, the following factors are known to increase an individual’s risk:
- Age: While people of any age can contract the disease, it is more common after age 50 and its frequency increases with each successive decade.
- Presence of Polyps: Polyps, of which there are different types, are common in people over age 50. The kind of polyp known as an adenoma is considered a precursor to cancer, so its presence, detected by a colonoscopy, indicates the likelihood of developing cancer.
- Previous Colon Problems: Men who have already had colon cancer or who have had inflammatory bowel disease such as Crohn’s Disease or Ulcerative Colitis, are at increase risk for colon cancer.
- Family History: The parents, siblings, or children of anyone who has had colorectal cancer or polyps is at increased risk.
- Diet: There is some indication that a low-fiber, high-fat, high-calorie diet increases risk.
- Smoking: Smokers appear to be at increased risk for the disease.
- Alcohol: Drinking increases risk for the disease.
- Sedentary Lifestyle: Regular exercise can help reduce the risk.
- Excess Bodyweight: Too much body fat appears to increase risk.
- Presence of Diabetes: Men suffering from diabetes are 30-40% more likely to get colon cancer than men without diabetes.
Colon Cancer Prevention
The following steps can be taken to reduce your risk of colorectal cancer:
- Aspirin: People taking aspirin regularly show reduced incidence of the disease. However, aspirin may induce dangerous internal bleeding or other medical problems in some individuals and possible negative interactions with other medications. So consultation with a physician is always recommended before beginning an aspirin regimen. When a doctor recommends aspirin for this purpose, the dose is generally one baby aspirin (81 mg) per day.
- Exercise: If you are sedentary, begin exercising. Regular exercise has been shown to decrease the risk of colorectal cancer by up to 40%. Its effectiveness appears related to the fact that people who exercise regularly eliminate waste from the colon more quickly than do sedentary people, which reduces the toxic effects of the waste on the colon. Also, exercise reduces the incidence of obesity and diabetes, which are independent risk factors for colon cancer.
Before beginning an exercise program, it is important to determine if you need a physician‘s clearance. Our Exercise Risk Questionnaire will help you determine whether you are ready to start exercising or whether you need a physician’s clearance to begin.
If you are healthy enough to exercise, your goal should be at least 30 minutes of physical activity 5 or more days per week. The preferred exercises are those that are continuous like walking, running, rowing, swimming, and bicycling. However, you will still get benefit from discontinuous forms of exercise like gardening, housecleaning, home-repair, golfing, bowling, tennis, weight-lifting, and softball. The most important thing is to become more active.
Despite the importance of physical activity, it is not advisable to suddenly begin exercising 30 minutes a day if you have been very sedentary. Rather, you should gradually increase the duration and intensity of exercise at a rate that you can handle without excessive strain. Increasing the duration or intensity of exercise too rapidly can lead to problems like stress fractures, tendonitis, muscle tears, and even cardiovascular problems, which would obviously defeat the purpose of becoming more healthy. So be patient. Start exercising if you are healthy enough to do so, and allow yourself time to increase the duration and intensity of exercise as you become more fit. See our general physical fitness program guidelines.
- Don’t Smoke: If you smoke, quit! Most smokers know that smoking is bad for their health and the health of those around them. Yet the habit is very difficult to break. For help, see our list of proven ways to quit smoking.
- Follow a Healthy Diet: The National Cancer Institute recommends a low-fat diet rich in fruits, vegetables, and whole grains to lessen risk.
- Get Screened: Screening tests, in order of invasiveness include fecal occult blood test, rectal exam, sigmoidoscopy, and colonoscopy. If you provide your doctor with full medical history information about you and your immediate relatives, the tests appropriate for you can be selected. Anyone with the risk factors listed above may need testing as early as age 12. The latest age at which anyone should get a first colonoscopy is 50. Depending on the results of the exam, the physician will recommend when the next colonoscopy should occur, usually within 3-5 years.
- If you are obese, lose weight: Men who are obese (Body Mass Index (BMI) above 30) are at increased risk for colorectal cancer. Also, even if your BMI does not place you in the obese category, if you carry excess fat around the waist, you are at increased risk. See if your waist measurement or waist-to-hip ratio is excessive. If you are obese or carry excess body fat around the waist, see our list of the most effective weight-loss methods.
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