Mayo Clinic Research Trials Lead to New National Colon Cancer Screening Guidelines

Wednesday, March 12, 2008

ROCHESTER, Minn. — On March 5, the American Cancer Society, the U.S. Multi Society Task Force on Colorectal Cancer and the American College of Radiology endorsed the use of two colon cancer diagnostic procedures tested and developed at Mayo Clinic for use in colorectal cancer screening. The procedures include CT colonography and a stool DNA test.

The new guidelines appear in the current issue of CA: A Cancer Journal for Clinicians. The guidelines state, that when possible, clinicians should make patients aware of the full range of screening options, but at a minimum they should be prepared to offer patients a choice between a screening test that is effective at both early cancer detection and cancer prevention through the detection and removal of polyps, and a screening test that primarily is effective at early cancer detection.

CT colonography, also known as virtual colonoscopy, underwent rigorous studies at Mayo Clinic for more than 10 years, while the stool DNA test was conceived and developed by Mayo Clinic researchers.

C. Daniel Johnson, M.D., chair of the Department of Radiology at Mayo Clinic's campus in Arizona, who led the CT colonography research, conducted the first clinical trials of CT colonography in 1996. Dr. Johnson, with research and clinical colleagues from throughout Mayo Clinic and other institutions, have published numerous studies about CT colonography since the late 1990s.

"It is gratifying to see a technology develop from its infancy to full clinical utilization and national endorsement as a highly effective technique for detecting colorectal polyps and cancer. We hope it will contribute to improved colorectal cancer screening rates and a reduction in the prevalence of this disease," Dr. Johnson said.

Stool DNA testing with multiple markers for colorectal cancer screening was introduced by David Ahlquist, M.D., a Mayo Clinic specialist in gastroenterology, with collaborators at EXACT Sciences, a medical technology company based in Massachusetts.

"Now that stool DNA testing is included in the national guidelines, we will likely see a burgeoning of research to improve test performance and better define clinical algorithms. This should be exciting," Dr. Ahlquist said.

Leadership in the Mayo Clinic Department of Radiology stated that the approval of the tests represents a paradigm shift for the role of radiologists in preventing, not just detecting cancer. Robert Rizza, M.D., Mayo Clinic's director for research, affirmed that Mayo Clinic's role in influencing the guidelines are representative of a Mayo research priority: to improve patient care through advances in research.

In the United States, colorectal cancer is the third most common cancer diagnosed among men and women and the second leading cause of death from cancer. It is largely preventable by the detection and removal of adenomatous polyps. Survival significantly improves when the cancer is diagnosed while still localized.

CT COLONOGRAPHY
CT colonography uses a computerized tomography (CT) machine to take images of the colon, rather than using a scope inserted into the rectum to see inside the colon. Patients still undergo a bowel preparation to remove stool. If abnormalities are detected on CT colonography, patients will need to undergo conventional colonoscopy.

Mayo Clinic was the first institution to report in the scientific literature on the clinical effectiveness of CT colonography, and the first to offer it for routine care. Mayo Clinic physicians in Minnesota and Arizona have performed more than 4,000 CT colonographies, more than any other medical center.

Dr. Johnson and colleagues recently completed a national CT colonography trial, which was sponsored and funded by the National Cancer Institute (NCI). The trial assessed the procedure's performance for large adenomas and advanced neoplasia in a screening of 2,500 patients across 15 institutions.

STOOL DNA TESTING
In 2000, Dr. Ahlquist and colleagues were the first to publish results demonstrating the feasibility of multi-target stool DNA testing for detection of colorectal cancers and premalignant polyps.

In a recently completed multicenter study funded by the NCI, Dr. Ahlquist and colleagues demonstrated that stool DNA testing detects unsuspected colorectal cancer and polyps at significantly higher rates than do common fecal occult blood tests. Preliminary results from his current studies suggest that stool DNA testing can also effectively detect common cancers above the colon, and that these findings could lead to a conveniently singular, noninvasive screen for cancers of the respiratory tract and upper digestive tract.

While stool DNA testing is endorsed for average risk colorectal cancer screening in the new guidelines, several key questions and implementation issues remain. Screening frequency is not yet defined, the FDA has not approved any specific kit for general use, most third party payors do not cover, and the management of patients who are stool DNA test-positive but colonoscopy-negative has not been elaborated.

DISCLOSURE:
In accordance with the Bayh-Dole Act of 1980, Mayo Clinic holds intellectual property rights in inventions or patents arising from research conducted using federal research funding and has a royalty sharing policy whereunder any royalties received from licensing rights to any such inventions or patents will be shared with the individual inventors. Mayo Clinic holds CT colonography patent rights, which have been licensed to GE Medical Systems and to E-Z-EM, Inc., and receives or may receive royalties from those licenses. Dr. Johnson is an inventor in connection with Mayo Clinic's CT colonography patent rights and as such receives a share of any royalties received by Mayo Clinic.

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