HER2 positive breast cancer is a subtype of breast cancer characterized by the overexpression of the HER2 protein. The HER2 gene, also known as ERBB2, is responsible for the production of the HER2 protein, which is a receptor on the surface of breast cells. This protein promotes the growth and division of cells. In HER2 positive breast cancer, an excess of HER2 protein leads to rapid and uncontrollable cell proliferation, resulting in tumor formation.
