Virginia Commonwealth University

VCU Massey Cancer Center

Screening guidelines

The guidelines for colorectal cancer screening are a set of recommendations prepared by an expert group representing a broad spectrum of health care organizations, including the American College of Gastroenterology, the American Society for Gastrointestinal Endoscopy and the American Cancer Society.

The guidelines offer recommendations for different options for colorectal cancer detection and emphasizes the prevention of colorectal cancer through screening.

Virtual colonoscopy one of two screening methods added for detecting colorectal cancer

The recommendations add two new screening methods to the other options available to the consumer. Fecal DNA testing and computed tomography (CT) colonography, also known as virtual colonoscopy, are the newly endorsed tests. Both are less invasive than other screening tests and should encourage patients to have tests that can find both polyps and most cancers.

Excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in men and women in the U.S. It is also the third leading cause of death from cancer.

Studies show that 50 percent of Americans who should be getting screening for this largely preventable disease are not getting tested. This despite data showing that screening saves lives. Even though rates of colorectal cancer have been declining over the past few years, they could be even lower if all people who should be screened actually got screened.

About the tests

A virtual colonoscopy uses a CT scan to search for abnormal masses. It does not require the insertion of the tube with a camera on the end into the rectum, which is what happens in traditional colonoscopy.

The fecal DNA test is used to check for specific changes in DNA that are typically found in colon cancer. All the patient needs to do is collect an entire bowel movement, then the sample is sent to a laboratory. In one clinical study, this test demonstrated better sensitivity for cancer and polyps with high-grade dysplasia when compared to fecal occult blood testing (an accepted colon cancer screening test). However, neither test performed very well for finding large polyps without high-grade dysplasia (earlier pre-malignant stage).

Since the fecal DNA test is fairly new, more research is needed to determine how often the test should be done to have the best possibility of finding cancer. Also, the test may be limited in finding every DNA change associated with cancer.

Bottom line is that all of these tests have their pros and cons and are good additions to options for colorectal cancer screening.

Current guidelines

The guidelines outline four testing procedures that are most likely to detect both polyps and cancer. They are:

  • Flexible sigmoidoscopy every five years.
  • Colonoscopy every 10 years.
  • Double contrast barium enema every five years.
  • CT colonography every five years.

A flexible sigmoidoscopy is a diagnostic procedure that allows the physician to examine the inside of a portion of the large intestine and is helpful in identifying the causes of diarrhea, abdominal pain, constipation, abnormal growths and bleeding. A short, flexible, lighted tube, called a sigmoidoscope, is inserted into the intestine through the rectum.

A colonoscopy is a test that uses a colonoscope, or long, flexible tube with a light and camera lens at the end, to examine inside the large intestine.

Colonoscopy still the best option

In spite of the experts’ recommendations for the use of newer technologies to screen for colorectal cancer, the groups continue to agree that colonoscopy is the preferred method of screening, as in the past. Colonoscopy has great sensitivity in both detecting polyps and removing them, making the procedure both diagnostic and therapeutic.

Colonoscopy is considered to be one of the most effective preventive tools in clinical medicine.

Follow-up for suspicious findings

If there are any positive findings from fecal tests, barium enema exams or CT colonography, follow-up will be required. For a positive result from a fecal test, a follow-up colonoscopy will also be required.

If physicians discover adenomas (benign growths which often appear on glands or in glandular tissue) during sigmoidoscopy, that procedure should be followed by colonoscopy. This is because research suggests that patients who have an adenoma of any size in the colon are at an increased risk for developing cancer cells higher up in the colon.

Following virtual colonoscopy, the guidelines state that the risk for patients whose polyps are small (smaller than 5 millimeters, or about 0.2 inch) is low, but for larger polyps (over 5 mm.) a follow-up colonoscopy is recommended.

Always consult your physician for more information.

For more information

Do you have a question for Massey’s experts in colorectal cancer? Want to know if there are clinical trials available? Simply click to Ask Massey.

If you want to read the full report on screening guidelines, click the title below.

Screening and Surveillance for the Early Detection of Colorectal Cancer and Adenomatous Polyps, 2008: A Joint Guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology