Did you know that you may be able to reduce your risk for a leading type of cancer by making changes in your lifestyle?
Colon cancer is cancer of the large intestine (colon), which is the lower part of your digestive system. Rectal cancer is cancer of the last few inches of the colon (rectum). Together, they're referred to as colorectal cancer.
Cancer of the colon and rectum occur when malignant (cancer) cells in the large intestine divide uncontrollably, causing a tumor or mass to form. These cancerous cells may invade surrounding tissue or spread to other parts of the body.
Doctors don't know exactly what causes most cancers of the colon. But you may be able to prevent colon cancer by taking steps to reduce your risk factors.
Experts believe that most colorectal cancers develop from polyps. Polyps are abnormal growths in the inner wall of the colon or rectum. They are somewhat common in people over 50 years old. Most are not cancerous. But some polyps, also called adenomas, do develop into cancer. If these are detected early through screenings, they can be removed before they turn into cancer. This is why regular screenings are so important.
Certain people are at an increased risk of colorectal cancer. People over 50 or with a family history of colorectal cancer are in this category. So are those with a personal history of inflammatory bowel disease or this type of cancer. If you drink three or more alcoholic drinks a day, if you smoke, or if you are obese, you're putting yourself at higher risk.
Some risk factors for colon cancer can't be changed — such as being older than 50 or having a family history of the disease. However, there are some things you can control.
The National Cancer Institute lists the following protective actions that lower the risk of colorectal cancer:
- Physical activity. A lifestyle that includes regular exercise has been shown to cut your risk.
- Aspirin. Taking aspirin every day for at least 5 years has been linked to a decreased risk of getting colorectal cancer and dying from colorectal cancer. However, aspirin therapy is not right for everyone. It can cause bleeding in the stomach, intestines or brain. Talk to your doctor about this therapy.
- Hormone replacement therapy. Research has shown that hormone replacement therapy that includes both estrogen and progesterone reduces the risk of colon cancer in postmenopausal women. It does not appear to lower the risk of rectal cancer. Nor does hormone therapy with estrogen alone lower the risk. However, be aware that hormone use increases the risk of breast cancer, heart problems and blood clots.
- Polyp removal. Most colorectal polyps are adenomas, which may develop into cancer. Removing colorectal polyps that are bigger than 1 centimeter may reduce the risk of colorectal cancer. It is not known if removing smaller polyps lowers the risk of colorectal cancer.
The factors above, experts say, are all actions you can consider. Other lifestyle choices may also reduce your risk of getting this type of cancer.
- Watching your weight. Obesity raises the risk of these cancers in both men and women. However, the risk appears to be higher in men. Having more belly fat appears to raise your risk even more. Maintain a healthy weight throughout life by balancing your calorie intake with physical activity.
- Eating a healthy diet. The American Cancer Society recommends eating plenty of fruits, vegetables, whole grains and fiber, and limiting your intake of red meat and processed meats. Be sure to get the recommended levels of calcium and vitamin D. More research is needed to understand the role of diet and vitamin supplements in colon cancer.
- Increasing the intensity of your exercise. The society recommends that adults get at least 30 minutes of moderate physical activity on most days of the week. There is some evidence that adding vigorous activity, such as jogging, may have an added benefit. You should also work in some form of strength-training at least twice a week. Check with your doctor before you increase your activity level.
- Quitting tobacco use. Smoking is linked to an increased risk of colon cancer. If you smoke, talk to your doctor about using nicotine replacement therapy and finding support to help you quit.
- Limiting alcohol. Drinking alcohol in excess may increase your risk. If you drink, have no more than one drink a day if you're a woman or two drinks a day if you're a man.
These are all lifestyle choices that we can control. As a bonus, for most people, these actions help the body in many healthy ways.
Screening: a strong prevention tool
Cancer screening is the process of looking for cancer in someone who has no symptoms. It is one of the best tools we have to prevent colon cancer.
Screening tests can find polyps early, before they become colon cancer. These tests can also detect cancer at an early stage when it can still be cured.
Doctors recommend that colon screening begin at age 50 and continue until age 75. If you have a strong family history of colon cancer, have inflammatory bowel disease or have had an adenomatous polyp at an early age, you may need to be screened earlier. Talk with your doctor about which colon screening plan is best for you.
Screening tests for colon cancer include a fecal occult blood test, a flexible sigmoidoscopy or a colonoscopy. Here is an explanation of these tests.
- A fecal occult blood test detects hidden blood in the stool (feces). Blood vessels in a polyp or cancerous growth can be easily damaged by passing stool, but you may not be able to see the blood. You can do this test at home using a kit from your doctor. You smear a sample of stool on a card or put it in a tiny vial and mail it to a lab for testing.
Before you do the test, make sure you understand and follow the instructions. Depending on the type of test, some foods and drugs may affect the test results.
If you choose to do this test, it should be repeated every year. If the test is positive, you will need to have a colonoscopy to look for the cause of the bleeding.
Some patients prefer to use this test because it is less invasive and less expensive than other methods. Your doctor will know if it's appropriate for you.
- A colonoscopy and a flexible sigmoidoscopy are procedures that use a long, thin flexible tube with a light and a tiny video camera. They allow a doctor to see the inside of the large intestine colon. With a sigmoidoscopy the doctor can examine only the last part of the colon and rectum. With a colonoscopy the doctor can examine the entire colon. If a polyp is found, it can be removed and sent to the lab to find out if it is cancer. If a polyp or cancer is found during sigmoidoscopy, a colonoscopy will be needed to look for other growths in the rest of the colon.
A sigmoidoscopy is usually repeated every 5 years and a colonoscopy every 10 years.
Talk to your doctor about what type of screening is best for you given your age and your history of previous screenings.
Louis Neipris, MD, contributed to this report.
Created on 08/24/1999
Updated on 01/28/2013
- United States Preventive Services Task Force. Screening for colorectal cancer.
- National Cancer Institute. Tests to detect colorectal cancer and polyps.
- American Cancer Society. Can colorectal cancer be prevented?