# What is HER2-positive?

Source: https://oncologyistanbul.com/glossary/her2-positive

> A subtype of breast (and some other) cancers where tumor cells have extra copies of the HER2 gene, making them grow faster but also targetable by specific drugs.

HER2 (human epidermal growth factor receptor 2) is a protein that, when overexpressed, drives faster tumor growth. Testing tumor tissue for HER2 status is standard practice because HER2-positive cancers respond to targeted therapies (like trastuzumab-based drugs) that HER2-negative cancers do not.

## Related
- [Breast cancer treatment](https://oncologyistanbul.com/cancers/breast)
- [HER2+ targeted therapy — per cycle price](https://oncologyistanbul.com/prices#her2-targeted-therapy-per-cycle)

## Authoritative references
- [Wikipedia](https://en.wikipedia.org/wiki/HER2)
- [Wikidata](https://www.wikidata.org/wiki/Q415271)

Full glossary: https://oncologyistanbul.com/glossary