Del Rosario, Kristina M

Abstract Objectives We investigated the impact of our laboratory’s reflex testing process for resolving ERBB2 (HER2) status on breast cancer samples that require additional workup after fluorescence in situ hybridization (FISH), per guideline recommendations published in 2018 by the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP). Methods In total, 500 breast cancer specimens with ERBB2 FISH results in groups 2 through 4 (all reported as immunohistochemistry [IHC] equivocal [2+] at external laboratories) were resubmitted for IHC testing in our laboratory. Per the ASCO/CAP guideline, FISH was rescored when internal IHC was also equivocal (2+), targeted to tumor areas demonstrating more intense IHC staining, if observed. Results Reflex IHC/FISH testing changed the final reported ERBB2 status in 185 of 500 (37.0%) samples. Result changes included discordant IHC (n = 4 score 0, n = 132 score 1+, and n = 16 score 3+) and discordant FISH (n = 33). Numerical differences in FISH scores were comparable for targeted vs nontargeted FISH rescoring (P = .086 for ERBB2 copy number; P = .49 for ERBB2 ratio). Two cases showed larger differences in FISH scores, suggesting heterogeneity. Conclusions Retesting of breast cancer samples with equivocal IHC frequently changes IHC results, but targeted reanalysis of borderline FISH results rarely identifies significant differences in ERBB2 copy number or ratio.

BACKGROUNDThe amount of time available to pathologists with which to perform research is becoming limited due to an increasing manpower shortage in pathology, decreased reimbursement, and increased workload. This is occurring at the same time as demands escalate for pathologists to develop new companion tests, correlate the molecular findings with traditional methods, and assist in the development of individualized medicine. This study examined whether cytotechnologists may be integrated into a research team that uses their expertise in understanding pathology and clinical disease to provide interpretations of experiments that traditionally were performed by pathologists.METHODSCytotechnologists worked with pathologists to choose blocks for tissue microarrays (TMAs) and to interpret immunohistochemically stained TMA slides. The pathologist met with the cytotechnologist to review the study design. The cytotechnologists reviewed the slides and blocks and chose the most appropriate blocks for the TMA. Either 10% or all of the slides/blocks selected for TMA construction were reviewed by the supervising pathologist. The final selections were given to the TMA technologist to make the TMA. A minimum of 10% of the immunohistochemically stained TMA slides were reviewed by the supervising pathologist.RESULTSA total of 32 TMAs were created with 6 cytotechnologists collaborating with 6 pathologists. Immunohistochemical stains of 190 TMAs were interpreted by 4 cytotechnologists collaborating with 3 pathologists. All the TMAs and TMA interpretation data were used successfully for the research for which they were designed.CONCLUSIONSThe collaboration of cytotechnologists and pathologists in research can improve the quality of effort and increase satisfaction and productivity. Cancer Cytopathol 2018;126:232‐5. © 2018 American Cancer Society.