HER2-positive breast cancers have a lot of a protein called HER2 on the surface of their cells. The HER2 protein is an important part of the pathway for cell growth and survival.

All breast cancers are tested for HER2 status. About 10-20 percent of newly diagnosed breast cancers are HER2-positive. HER2-positive breast cancers can be treated with HER2-targeted therapies.

HER2-targeted therapies for early breast cancer include trastuzumab, known as Herceptin, ado-trastuzumab emtansine, or Kadcyla, pertuzumab, which is Perjeta, and neratinib, also known as Nerlynx.