By Carol Weinman, Pure Matters
Colorectal cancer is the second most common cause of cancer deaths for men and women combined. When men and women are considered separately, colorectal cancer is the third most common cause of death in each sex, according to the American Cancer Society (ACS). (For men and women, lung cancer is the leading cause of cancer deaths, prostate cancer is the second leading cause for men, and breast cancer is the second leading cause for women.)
Your risk for developing colorectal cancer increases with age, but other lifestyle factors and genetics also play a role in increasing risk.
The risk for colorectal cancer increases after age 40. The risk rises sharply beginning around age 50 and continues to increase with each passing decade.
Because colorectal cancer develops slowly, the ACS emphasizes screening for the early detection of pre-cancerous polyps. Early detection focuses on finding and removing a type of polyp in the colon called an adenoma, which is the precursor to colon cancer in most cases. If these are found early and removed, the cancer can be prevented.
Researchers say that diet seems to affect your risk for developing colorectal cancer. People whose diets are high in fat (especially fats from animal sources) and processed meats are at higher risk for colorectal cancer. It is currently not known if taking folic acid or Vitamin D lowers the risk of colorectal cancer. Although fiber was thought to aid in prevention of colorectal cancer, studies have shown conflicting results.
Obesity can increase the risk for colorectal cancer, and so can smoking and heavy alcohol use, according to the ACS and the National Cancer Institute.
A sedentary lifestyle has been linked to an increased risk for colorectal cancer. The ACS has recommended at least 30 minutes, and even better, 45 to 60 minutes of physical activity on five or more days of the week to lower the risk of getting colorectal cancer.
Some studies show that using nonsteroidal anti-inflammatory drugs, including aspirin, may help reduce the risk for colon cancer. This is not an accepted indication for their use at this time because of their potential side effects. Don't begin taking these medications to prevent colon cancer without first talking to your doctor about these medications, particularly for long-term use.
The ACS recommends that screening for colorectal cancer begin at age 50 for people at average risk. If you are at increased risk for colorectal cancer (for example, you have a family history of colorectal cancer), talk with your health care provider about which screening method is right for you, when you should begin screening, and how often you need it.
Here is more information about tests that are available:
- The stool blood test, called the fecal occult blood test (FOBT) or the fecal immunochemical test (FIT), looks for small amounts of blood in the stool. These tests are done at home, and they require that the person takes several samples. At least one sample should be taken on three different days. For the FOBT, the test should be taken after two days on a diet free of meat, aspirin, and iron. These samples are then sent to a laboratory for testing. If blood is found, additional testing with a vitamin C, colonoscopy will be needed to find the source of the blood. Although these tests have led to early diagnosis of polyps or colon cancer, there is a significant incidence of "false positives" (the test is positive, but you do not have a polyp or cancer) and of "false negatives" (the test is negative, but you have a polyp or cancer that was not detected).
- For a stool DNA test, you will submit an entire bowel movement to a lab, which examines it for abnormal gene changes in any colon cells in the sample. This is an expensive test to have done. Because it is so new, experts aren't yet sure how often it needs to be done.
- With a flexible sigmoidoscopy, the doctor uses a thin, lighted tube called a sigmoidoscope to look into the rectum and about half of the colon for polyps. This test often is uncomfortable, but shouldn't be painful, the ACS says. Recent research has found that because women may be more likely to have colon cancer occur in a part of the colon not examined by a sigmoidoscopy, sigmoidoscopy may not be as effective a screening test for women.
- In a colonoscopy, the doctor uses a longer version of the sigmoidoscope to explore the entire length of the colon. This device also allows the doctor to remove any polyps that may be found. These are tested for cancer. Like the sigmoidoscopy, this test may be uncomfortable. Medicine is available to keep you relaxed and minimize the discomfort.
- A barium enema with air contrast allows the doctor to take an X-ray of the colon to find polyps. For this test, barium partly fills the colon and air is pumped in to expand the colon, the ACS says. This test is useful for those unable or unwilling to have a colonoscopy, and is reliable when done by a skilled and experienced diagnostic radiologist or gastroenterologist. But if something abnormal is seen on the test, a colonoscopy will be needed.
- Virtual colonoscopy, a new method of screening for colorectal cancer, produces 3-D images of the colon. Computed tomography, sometimes called a CAT scan, is used to create the image. While this test is not as invasive as a colonoscopy, it still requires that the bowel be cleaned beforehand with enemas and/or laxatives. If a a mass is detected, traditional colonoscopy or surgery is needed to remove it.
All of these tests, except for FOBT, FIT, and stool DNA tests, require you to go through a process to cleanse stool from the colon and rectum the day before the test. Your health care provider will give you the instructions on how to do this.
The ACS says you are at increased risk for colorectal cancer if:
- A parent, brother, sister or child has had it. The risk is further increased if the cancer developed before age 60.
- You have a genetic abnormality called familial adenomatous polyposis or one called hereditary nonpolyposis colorectal cancer.
- You have had colorectal cancer.
- You have a personal history of colon polyps.
- You have or have had ulcerative colitis or Crohn's disease.
- You have type 2 diabetes.
- You are obese.
- You are a heavy drinker.
- You smoke.
ACS guidelines for people of average risk say that both men and women should get one of the following. Talk to your doctor about which screening method is appropriate for you.
- A yearly FOBT or FIT, or
- A flexible sigmoidoscopy every five years, or
- A virtual colonoscopy every five years, or
- A double contrast barium enema every five years, or
- Colonoscopy every 10 years
- A stool DNA test (best interval uncertain)