Colorectal Cancer Early Detection
The American Cancer Society believes that preventing colorectal cancer (and not just finding it early) should be a major reason for getting tested. Finding and removing polyps keeps some people from getting colorectal cancer. Tests that have the best chance of finding both polyps and cancer are preferred if these tests are available to you and you are willing to have them.
According to the American Cancer Society, beginning at age 50, both men and women at average risk should follow one of these screening tests below:
Tests that find polyps and cancer
- Flexible sigmoidoscopy every 5 years*
- Colonoscopy every 10 years
- Double-contrast barium enema every 5 years*
- CT colonography (virtual colonoscopy) every 5 years*
Tests that mainly find cancer
- Fecal occult blood test (FOBT) every year*,**
- Fecal immunochemical test (FIT) every year*, **
- Stool DNA test (sDNA)***
*Colonoscopy should be done if test results are positive.
**For FOBT or FIT used as a screening test, the take-home multiple sample method should be used. An FOBT or FIT done during a digital rectal exam in the doctor's office is not adequate for screening.
***This test is mentioned because it was a part of the ACS guidelines published in 2008, but it is no longer available.
Is a rectal exam enough to screen for colorectal cancer?
In a digital rectal examination (DRE), a doctor examines your rectum with a lubricated, gloved finger. Although a DRE is often included as part of a routine physical exam, it is not recommended as a stand-alone test for colorectal cancer. This simple test, which is not usually painful, can detect masses in the anal canal or lower rectum. By itself, however, it is not a good test for detecting colorectal cancer because its reach is limited.
Doctors often find a small amount of stool in the rectum when doing a DRE. However, simply checking stool obtained in this fashion for bleeding with an FOBT or FIT is not an acceptable method of screening for colorectal cancer. Research has shown that this type of stool exam will miss more than 90% of colon abnormalities, including most cancers.
People at increased or high risk
If you are at an increased or high risk of colorectal cancer, you should begin colorectal cancer screening before age 50 and/or be screened more often. The following conditions make your risk higher than average:
- A personal history of colorectal cancer or adenomatous polyps
- A personal history of inflammatory bowel disease (ulcerative colitis or Crohn's disease)
- A strong family history of colorectal cancer or polyps (see “Risk factors for colorectal cancer”)
- A known family history of a hereditary colorectal cancer syndrome such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colon cancer (HNPCC)
Your doctor can suggest the best screening option for you, as well as any changes in the schedule based on your individual risk.