Colorectal Cancer: Prevention


When colorectal cancer is detected early, it can often be cured. The death rate from this type of cancer has been declining for the past 20 years, possibly because more cases are being detected early and treatments have improved.

People in their 50s and older should be screened, and certain people should begin colorectal cancer screening earlier and/or undergo screening more often if they have the following:

  • A personal history of colorectal cancer or adenomatous polyps
  • A strong family history of colorectal cancer or polyps (cancer or polyps in a first-degree relative younger than 60 or in two first-degree relatives of any age). A first-degree relative is defined as a parent, sibling or child.
  • A personal history of chronic inflammatory bowel disease
  • A family history of hereditary colorectal cancer syndromes
  • If immediate family is diagnosed before age 50, other family members should be tested at least ten years earlier; i.e. if an individual’s father is diagnosed at age 45, then the children should be screened starting at age 35.

Tests used to screen for colorectal cancer include:

Fecal Occult Blood Test (FOBT)

A test used to detect blood in the feces (stool), which can indicate the presence of polyps or cancer. Polyps and cancers do not bleed continually, so the FOBT must be done on several stool samples each year and should be repeated annually. This test has low sensitivity for detecting colon cancer and should not be used alone in screening colon cancer.

Flexible Sigmoidoscopy

A sidmoidoscope (lighted tube) is inserted into the rectum and lower colon to check for polyps, cancer and other abnormalities. During this procedure, a doctor can remove polyps or other tissue for later examination. The doctor cannot check the upper part of the colon (ascending and transverse colon) with this test. If polyps or cancer is detected using this test, a colonoscopy to view the entire colon is recommended.


This test allows the doctor to look inside the entire rectum and colon while a patient is sedated. A colonoscope (lighted tube) is inserted into the rectum and the entire colon to look for polyps or cancer. During this procedure, a doctor can remove polyps or other tissue for examination.

Double Contrast Barium Enema (DCBE)

For patients who cannot have a colonoscopy, an enema containing barium is given, which helps the outline of the colon and rectum stand out on x-rays. A series of x-rays is then taken of the colon and rectum. This test has not been shown to improve outcomes and therefore is not a preferred screening approach.


Computed tomography (CT or CAT) colonography and fecal DNA tests are experimental screening methods. CT colonography is offered in some institutions, but people should be aware that it is still considered to be under development and requires interpretation by a skilled radiologist in order to be used to its best advantage.

Beginning at age 50, both men and women of average risk should follow one of these four testing schedules:

  • Yearly fecal occult blood test (FOBT)
  • Flexible sigmoidoscopy every five years
  • Yearly fecal occult blood test plus flexible sigmoidoscopy every five years
  • Colonoscopy every 10 years