HER2-low
A breast cancer subtype with low HER2 protein expression, recently recognized as a distinct therapeutic target.
Full Definition
HER2-low breast cancer represents a newly defined subtype characterized by immunohistochemistry scores of 1+ or 2+ with negative in situ hybridization (ISH) testing. This classification emerged with the development of antibody-drug conjugates like trastuzumab deruxtecan, which demonstrated efficacy in HER2-low tumors despite traditional classification as HER2-negative. HER2-low tumors comprise approximately 55% of breast cancers previously considered HER2-negative, representing a significant patient population with novel treatment options.
Usage
Usage note: Hyphenate HER2-low. This is a recent classification that differs from traditional HER2-negative categorization.
In Context
- "The HER2-low classification qualified the patient for trastuzumab deruxtecan therapy." — Pathology report
- "HER2-low breast cancers represent a newly targetable population previously considered HER2-negative." — Clinical research abstract