Dr. Pincus on Classifying HER2+ Tumors in Breast Cancer

Jenny Pincus, MD, assistant professor of pathology, Northwestern University, Feinberg School of Medicine, discusses the classification of HER2-positive tumors in patients with breast cancer.

As a pathologist, Pincus tests for HER2 via immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) testing to give prognostic information to clinicians. If the tumor is equivocal by IHC, Pincus says that a FISH test is then performed. The FISH test will then be positive, equivocal, or negative. With this information, clinicians can then decide on the appropriate treatment plan for the patient.

Most tumors can be classified by those 2 methodologies, but occasionally tumors will be deemed double-equivocal. Investigators at Northwestern University have done research on this occurrence. Pincus says that investigators found that using alternate probes that check a different area of the gene, rather than close to the HER2 receptor, are often able to identify whether the tumor is truly amplified for HER2.