Novel Predictive Biomarkers for Non-Small Cell Lung Cancer - Episode 3

Adequate Tissue Collection for Molecular Testing in NSCLC


Greg Riedlinger, MD, PhD: To ensure that proper and adequate material is obtained from a biopsy, for all diagnostic biopsies most institutions will employ a cytotechnologist, a cytology fellow, or a cytologist. An onsite adequacy assessment is performed, and that’s not 100% reliable but it gives us a good indication of these onsite aspirate assessments and whether the subsequent material, which will be made into a cell block or an actual core in formalin, will be adequate. That’s really the best that we can do. The other thing is we always, as pathologists, try to communicate to our colleagues that we want as much tissue as they’re comfortable giving us.

As a pathologist, to ensure that we have adequate tissue for all these downstream analyses, different protocols have been established to really make sure that with limited amounts of tissue biopsy, we are able to perform all of these tests. At Rutgers Cancer Institute, we’ve typically been getting adequate material. But one instance where you sometimes lose material, especially from the smaller biopsies such as the FNA [fine needle aspirate] cores, is when immunohistochemical stains will process some of the block and then the histotechnician has to go back and process more of the block. Up front, we actually know that we’re going to need a lot of this tissue for downstream molecular tests. We’ve set up protocols where 20 unstained slides will automatically be cut when we know that this is a lung adenocarcinoma that’s going to need some type of downstream molecular analysis. Oftentimes, we get multiple core biopsies, and one strategy people have employed—we’re not doing this currently—is actually splitting the cores between different tubes or different blocks. That way, it gives you a little bit more material from the multiple cores that are often obtained.

With the new guidelines that have come out from CAP [College of American Pathologists] and the Association for Molecular Pathology, it’s now also recommended—or with these newer guidelines, it’s OK—to perform testing on aspirate smears. With some of the older guidelines, that wasn’t a recommendation. That’s another source where you can potentially get material with the caveat being these new aspirates, if you’re going to perform any of the downstream molecular analysis, have to be validated the same way you would for blood or other tissue.

Transcript Edited for Clarity