Mayo Clinic cancer experts find gaps in current colorectal cancer screening approaches

Colorectal cancer remains the second leading cause of cancer death for men and women combined in the U.S. The goal of screening is to reduce the number of people who die from this common cancer. According to Mayo Clinic cancer experts there are gaps in current screening approaches in terms of detection accuracy, patient willingness to use them, and accessibility.

Recently, the U.S. Preventive Services Task Force (USPSTF) announced draft recommendations on colorectal cancer screening. The task force recommended screening for colorectal cancer using the conventional tools, including, fecal occult blood testing, sigmoidoscopy or colonoscopy in adults, beginning at age 50 years and continuing until age 75.

The task force concluded that the evidence is less mature to support use of the stool DNA test as a screening modality for colorectal cancer and designated this new test as an alternative rather than front-line screening approach. The innovative and noninvasive stool DNA test (Cologuard) was co-developed by Mayo Clinic and Exact Sciences scientists to improve screening accuracy, encourage participation with its user-friendly features, and remove access barriers. The stool DNA test has met the stringent reviews and been approved by both the US Food & Drug Administration (FDA) and Centers for Medicare and Medicaid Services (CMS). Mayo Clinic strongly urges the USPSTF to unambiguously support the stool DNA as a fully legitimate colorectal cancer screening option.

"There is compelling scientific evidence that this innovative approach can increase screening accuracy and potentially save lives," says John Noseworthy, M.D., President and CEO, Mayo Clinic. "We need to remove cost, cultural, location and other barriers to improve access to effective screening."

Colorectal cancer develops slowly over a period of 10 to 15 years. Consequently, there is an ample window for early detection by screening to reduce both the incidence and death rate from colorectal cancer. However, nearly half of the population has not been screened, in part, because of reticence to use or limited access to conventional tests. It is critical that there are accurate options available that patients and providers are willing and able to use.

The stool DNA test is a noninvasive new screening tool that identifies characteristic chemical changes in stool that signal the presence of either cancer or precancerous polyps. The test requires no bowel preparation, no diet or medication restrictions, and no missed work, as it can be done from home. In a large study published last year in the New England Journal of Medicine, stool DNA had sensitivity for early-stage cancer of 94 percent, which is the same as has been reported for colonoscopy, and was especially sensitivity for those largest polyps at greatest risk of progressing to cancer. It was significantly more sensitive in detecting both cancer and precancerous polyps than was fecal blood testing.

"Stool DNA screening is an effective new method designed specifically to fill gaps left by conventional screening approaches. Because this test is innovative, there has consequently been less medical literature generated than by the conventional tests that have been used over a long period historically. However, the well-done and peer-reviewed research fully supports use of this FDA approved approach. We would ask USPSTF to allow patients unfettered access to this new tool based on its merits," says Robert Diasio, M.D., Director, Mayo Clinic Cancer Center.

Mayo Clinic announced in 2015 that it would make stool DNA testing available as a primary screening method for its patients. "Part of our aim in adopting this screening method was to increase screening access and compliance and this approach does both," says Vijay Shah, M.D., chair, Mayo Clinic gastroenterology, who lead the group that oversaw implementation of stool DNA testing at the clinic. "Furthermore, we wanted our patients to benefit from stool DNA test's high detection rates of early stage cancer and polyps at greatest risk of progression, which is unprecedented for noninvasive tests."

Patients prescribed stool DNA screening at Mayo Clinic follow CMS (Medicare) guidelines. The guidelines call for a screen every three years in patients ages 50-85. Mayo Clinic experts further note that if the FDA approved CMS guidelines are followed, modeling shows that stool DNA screening causes fewer false positives, which lead to unnecessary colonoscopies, than annual fecal blood testing.