HER2 amplification
Also written as: HER2 — Human Epidermal Growth Factor Receptor 2
Overexpression of the HER2 protein due to gene amplification, determining eligibility for targeted HER2 therapies in breast cancer treatment.
Full Definition
HER2 amplification refers to the increased copies of the HER2/neu gene that result in overexpression of the HER2 protein on breast cancer cell surfaces. This molecular alteration occurs in approximately 15-20% of breast cancers and is detected through immunohistochemistry (scored 0, 1+, 2+, or 3+) and/or fluorescence in situ hybridization (FISH). HER2 amplification defines a distinct molecular subtype of breast cancer that responds to targeted therapies such as trastuzumab, pertuzumab, and T-DM1, making accurate determination crucial for treatment planning.
Usage
Usage note: Distinguish from 'HER2 positive' which is the clinical designation; amplification refers specifically to the molecular mechanism.
In Context
- "FISH analysis confirmed HER2 amplification with a HER2/CEP17 ratio of 3.2." — Pathology report
- "The patient is eligible for trastuzumab-based therapy given the HER2 amplification status." — Oncology treatment plan