abstract: Use of Mismatch Repair Immunohistochemistry and Microsatellite Instability Testing: Exploring Canadian Practices

METHODS:

Two web-based questionnaires were administered, a general and a specialist laboratory questionnaire, to establish the availability of such tests, requisite clinical/pathology integration, current mode of test initiation, reporting and recommendation practices, and education and attitudes among pathologists. Technical aspects were reviewed on the basis of specialist laboratory practice.

RESULTS:

Of 76 respondents, 21.5% were unaware or were uncertain whether they had access to MMR immunohistochemistry. Although 78.9% of respondents had access to such testing, an integrated approach to the identification of patients with LS is lacking, being limited to just 9 centers. The majority (70%) of testing is clinician initiated, with variable implementation of reflex testing and divergent practices in recommendation to test. Standardized reporting is lacking in many centers. Education on MMR in endometrial cancer is poor compared with that in colorectal cancer (P<0.0001).

(Blogger's Note: and so it would be safe to assume, based on this abstract, that the full spectrum of Lynch Syndrome related cancers requires obviously increased attention. As a further note, this and similar abstracts should take the opportunity to detail, in the background section, the full cancer spectrum - a one-line sentence is all that is required.)

INTERPRETATION:

This multicenter questionnaire highlights heterogenous practices in dMMR testing and LS identification, both in clinical terms and with regard to technical aspects of testing. An integrated multidisciplinary approach is lacking, and there is a need to educate physicians and resolve ethical issues. A Canadian consensus statement and national guidelines on dMMR testing are urgently needed, requiring input from pathologists, clinicians, and genetic counselors.