43. Considerations for implementation of the new ASCO/CAP guidelines for HER2 testing in the clinical laboratory

Human Epidermal Growth Factor Receptor 2 (HER2) testing provides important prognostic and predictive information for women with breast cancer. Approximately 5% of cases evaluated by FISH have hybridization patterns that are not clearly positive or negative. In 2018, the American Society of Clinical Oncology (ASCO) and College of American Pathologists (CAP) issued updated testing guidelines, which integrate concomitant IHC review for FISH cases with an unclear result (groups 2, 3, and 4), to make a final HER2 result determination.