Preventing Colon Cancer

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 doubles with each passing decade, the National Cancer Institute (NCI) reports.

Because colorectal cancer develops slowly, the NCI 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, the NCI says.

Reducing risk

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), protein, calories, alcohol and meat, and low in calcium and folate appear more likely to develop this type of cancer than are people whose diets are low in fat and high in fiber, the NCI says.  Although fiber was thought to aid in prevention of colorectal cancer, studies have shown conflicting results. A diet low in vitamin D may also increase the risk of colorectal cancer.

Obesity can increase the risk for colorectal cancer, and so can smoking, according to the ACS. 

A sedentary lifestyle has been linked to an increased risk for colorectal cancer. The U.S. Department of Agriculture recommends getting at least 30 to 60 minutes of exercise as many days of the week as possible.

Some studies show that using non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin, may help reduce the risk for colon cancer. This is not an accepted indication for their use at this time.  Don't begin taking these medications to prevent colon cancer without first talking to your doctor about these medications, particularly for long-term use.

A multivitamin with folate also may lower your risk for colorectal cancer, according to the ACS. Getting adequate calcium and vitamin D in your diet, either through increased amounts of low-fat dairy products fortified with vitamin D or through a calcium supplement with vitamin D, also may lower your risk.

Screening

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, talk to your health care provider about which screening method is right for you, when you should begin screening and how often you need it.

If you have a family history of colorectal cancer, talk to your doctor about screening tests and when you should receive them. 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, each taken after two days on a diet free of meat, aspirin, vitamin C and iron.

These samples are then sent to a laboratory for testing. If blood is found, additional testing 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).

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 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.

Virtual colonoscopy, a new method of screening for colorectal cancer, produces 3-D images of the colon. Either computed tomography (CT), sometimes called a CAT scan, or magnetic resonance imaging (MRI) is used to create the image. This test may become an effective screening tool for adults who are at average risk for colorectal cancer, but the ACS does not yet recommend it to replace the tests discussed above. It can only screen the colon for the presence of polyps. If a polyp is detected, traditional colonoscopy or surgery is needed to remove it.

All of these tests, except for FOBT or FIT, 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 are a Jew of Eastern European descent (Ashkenazi Jew).

• 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 diabetes.

• You smoke.

• You are female and have had breast, uterine or ovarian cancer.

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 fecal occult blood test, or

• A flexible sigmoidoscopy every five years, or

• A yearly FOBT or FIT and a flexible sigmoidoscopy every five years, or

• A double contrast barium enema every five to 10 years, or

• Colonoscopy every 10 years

Symptoms

If you have any of these symptoms, talk to your doctor, they may be caused by colorectal cancer or a non-cancerous condition. According to the ACS, symptoms of colorectal cancer may include:

• A change in bowel habits; this could be diarrhea, constipation or a narrowing of the stool that lasts for more than a few days

• A continuing feeling that you need to have a bowel movement

• Bleeding from the rectum, or blood in the stool

• Cramping or steady stomach pain

• Weakness or tiredness