According to briefing documents posted online Monday, scientists are evaluating the precision of mail-in, stool-sampling kits from Epigenomics and Exact Sciences, which if approved could be on the market this summer, Matthew Perrone writes for the Minneapolis Star Tribune.
Stool tests have long been employed to help detect precancerous tumors, and colon cancer is often treatable if found early enough. So far, the two tests are more accurate than traditional blood stool tests, but they also more often reported growths when there were none.
“Colorectal cancer is the second leading cause of cancer death in the U.S., with over 50,000 deaths expected this year, according to the American Cancer Society,” Perrone reports. Last year Kentucky had the fourth highest death rate for colon cancer in the nation, Dr. Amy Tiu noted in a March 15 article for the Lexington Herald-Leader.
Though colonoscopy is the most accurate screening, many people shun it because they think it will be uncomfortable or invasive, and a liquid compounds must be used to clean out the colon before the procedure. The blood-in-stool tests, though thought to be less accurate, may work just as well if employed each year, according to a federally appointed panel.
The new screenings are expected to be more expensive than traditional tests, and it is so far unclear how often people would need to be tested, Perrone reports.
“Only through a better understanding of other key factors, such as the screening interval, adherence, cost and diagnostic evaluation of positive results, can we determine the appropriate place for stool DNA testing on the screening menu,” Drs. Douglas Robertson Dr. Jason Dominitz said in the briefing documents.
One of the proposed tests, Cologuard, detected colorectal cancer in 92 percent of patients who had cancerous tumors, while the traditional blood stool test only has 74 percent accuracy. “In patients with precancerous polyps the test was accurate 42 percent of the time, compared with 24 percent for the blood test,” Perrone reports.
Epigenomics’ Epi proColon test, however, did not meet all of the study goals. This test discovered cancer in 68 percent of patients who had cancerous tumors, but it only recognized healthy patients in 79 percent of cases. FDA scientists warned that “lower specificity could lead to an increase in the number of avoidable colonoscopies” and “adverse events associated with such invasive procedures,” Perrone writes.