ORLANDO – A large percentage of U.S. gastroenterologists said that they don’t routinely order genetic testing for Lynch syndrome for patients with early-onset colorectal cancer, often because the physicians believe that the test is too expensive, or because they are unfamiliar with interpreting or applying the results, according to survey replies from 442 gastroenterologists.
Another factor hindering broader screening for Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer) is that many of the surveyed gastroenterologists did not see themselves as having primary responsibility for ordering Lynch syndrome testing in patients who develop colorectal cancer before reaching age 50 years, Jordan J. Karlitz, MD, and his associates reported in a poster at the World Congress of Gastroenterology at ACG 2017.
The survey results showed that only a third of the survey respondents believed it primarily was the attending gastroenterologist’s responsibility to order testing for Lynch syndrome using either a microsatellite DNA instability test or by immunohistochemistry. A larger percentage, 38%, said that ordering one of these tests was something that a pathologist should arrange, 15% said it was primarily the responsibility of the attending medical oncologist, and the remaining respondents cited a surgeon or genetic counselor as having primary responsibility for ordering the test.
This absence of a clear consensus on who orders the test shows a “diffusion of responsibility” that often means testing is never ordered, Dr. Karlitz said in a video interview. What’s needed instead is “reflex testing” that’s done automatically for appropriate patients, an approach that has become standard at several U.S. medical centers, he noted.
The survey Dr. Karlitz and his associates ran stemmed from a report they published in 2015 that focused on management of the 274 patients diagnosed with early-onset colorectal cancer in Louisiana during 2011, defined as cancers diagnosed in patients aged 50 years or younger. Data collected in the Louisiana Tumor Registry showed that Lynch syndrome testing occurred for only 23% of these patients, the researchers reported (Am J Gastroenterol. 2015 Jul;110:948-55).
To better understand the underpinnings of this low testing rate they sent a survey about Lynch syndrome testing by email in March 2017 to nearly 12,000 physicians on the membership roster of the American College of Gastroenterology. They received 455 replies, with 442 (97%) of the responses from gastroenterologists. When asked why they might not order Lynch syndrome testing for patients with early-onset colorectal cancer, 22% said the cost of testing was prohibitive, 18% blamed their lack of familiarity with the Lynch syndrome tests and how to properly interpret their results, and 15% attributed their decision to a lack of easy access to genetic counseling for their patients, with additional reasons cited by fewer respondents.
Dr. Karlitz noted that current recommendations from the National Comprehensive Cancer Network call for Lynch syndrome testing for all patients who develop colorectal cancer regardless of their age at diagnosis.
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