Accurate identification of HER2-positive patients is essential for superior outcomes with trastuzumab therapy.
OBJECTIVE
To review the clinical significance, methods of testing, and outcomes of trastuzumab (Herceptin) treatment for HER2 gene amplification and HER2 protein overexpression in breast cancer.


METHODS
Published articles and abstracts, online resources, a clinical handbook, and product information.


RESULTS
HER2 gene amplification or HER2 protein overexpression can be found in 20%-25% of breast cancers and is important pathogenic and prognostic information. HER2 also predicts patient response to trastuzumab. Patients with HER2-positive metastatic breast cancer benefit from trastuzumab whether selected by immunohistochemistry, which measures the HER2 protein, or fluorescence in situ hybridization (FISH), which measures the HER2 oncogene. However, patients who are identified accurately as HER2 gene-amplified by FISH derive the greatest benefit.


CONCLUSIONS
Accurate testing is crucial for appropriate identification of patients for trastuzumab therapy. FISH is the most reproducible and accurate method.


CONCLUSIONS
Education regarding HER2 testing and trastuzumab helps patients to make informed decisions and facilitates active participation in their care as well as enhances dialogue with physicians.
Chorn
Nathalie
N
Department of Medicine, University of California, Los Angeles, USA. nchorn@mednet.ucla.edu
D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000451:nursing; D004359:Drug Therapy, Combination; D005260:Female; D005784:Gene Amplification / Q000187:drug effects; D018734:Genes, erbB-2; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D009859:Oncology Nursing / Q000379:methods; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000187:drug effects / Q000378:metabolism; D000068878:Trastuzumab; D016896:Treatment Outcome
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab