Medical corner: Colorectal cancer screening

  • Published
  • By Dr. William F. Price
  • 71st Medical Group
Colon cancer is cancer of the large intestine, also called the colon. Rectal cancer is cancer of the rectum, which is the part of the large intestine closest to the anus. 

Because these cancers have many common features they are often referred to together as colorectal cancer. 

Colorectal cancer is the second leading cause of cancer deaths in the United States. Many of these deaths happen because the cancers are found too late to be effectively treated. If colorectal cancer is found early enough, it is usually very treatable and not life-threatening. 

The lifetime incidence of colorectal cancer in patients at average risk is about 5 percent, with 90 percent of cases occurring after age 50. 

Most colorectal cancers begin as a polyp. At first, a polyp is a small, harmless growth in the wall of the colon. However, as a polyp gets larger, it can develop into a cancer that grows and spreads. 

See your doctor if you have any of the following warning signs:
· Bleeding from your rectum
· Blood in your stool or in the toilet after you have a bowel movement
· A change in the shape or consistency of your stool -- such as diarrhea or constipation lasting several weeks
· Cramping pain in your lower stomach
· A feeling of discomfort or an urge to have a bowel movement when there is no need to have one
· Weakness or fatigue
· Unintended weight loss 

Other conditions can cause these same symptoms. You should see your doctor to find what is causing your symptoms. 

Screening tests can find polyps or cancers before they are large enough to cause any symptoms. Screening tests are important because early detection means that the cancer can be more effectively treated. Your doctor will choose the tests that are right for you.

The following are some screening tests for colorectal cancer:
· Digital rectal exam
· Check stool for blood
· Colonoscopy
· Barium enema
· Flexible sigmoidoscopy
· Stool DNA test
· Virtual colonoscopy, utilizing computerized tomography to create a three dimensional representation of your colon 

Of these tests, digital rectal exam, checking your stool for blood, and colonoscopy are the ones used in this community. Barium enema and flexible sigmoidoscopy are older exams not used much anymore. The last two -- virtual colonoscopy and stool DNA testing -- are specialized studies not done in this area. 

Colorectal cancer is more common in older people, so doctors usually screen people 50 years of age and older. Some people have risk factors that make them more likely to get colorectal cancer at a young age. Screening should begin earlier in these people. 

You should be screened for colorectal cancer at a younger age if:
· You have had colorectal cancer or polyps in the past
· You have a family history of colorectal cancer or polyps
· You have ulcerative colitis or Crohn's disease
· You have a hereditary colon cancer syndrome
· You eat a high-fat, low-fiber diet 

If you are in one of these groups, you may also need to be tested more often than a person who doesn't have risk factors for colorectal cancer. 

Any one of the screening programs, with a digital rectal exam at each screening, may be used every five to 10 years, beginning at age 50. 

Talk to your family doctor to decide which screening tests you should have and how often you should be screened. If you don't have any risk factors for colorectal cancer, you will probably have your first screening test around age 50. 

For more information, contact the American Cancer Society at or 800-227-2345.