Trastuzumab

Trastuzumab is a targeted therapy, meaning it is designed to act on a specific molecular target rather than attacking all rapidly dividing cells the way traditional chemotherapy does. Its target is the HER2 protein — a receptor that, when overexpressed on breast cancer cells, accelerates their growth and division. In HER2-positive breast cancers, this protein is present in abnormally high amounts.

By attaching to HER2 receptors, trastuzumab blocks the signals that tell cancer cells to grow. It also flags those cells for destruction by your own immune system. It is typically given by intravenous infusion and is often combined with chemotherapy or other targeted therapies, depending on the stage and characteristics of the cancer.

The development of trastuzumab was a landmark moment in oncology — one of the first demonstrations that targeting a specific molecular driver of cancer could dramatically improve outcomes. For people with HER2-positive breast cancer, which was once considered one of the more aggressive subtypes, trastuzumab and similar therapies have substantially changed survival statistics. Your oncologist can explain whether your tumor's HER2 status makes this type of treatment relevant for you.

HER2-positive breast cancer was once associated with a poorer prognosis, but the development of trastuzumab fundamentally changed the outlook for many patients. Clinical trials showed that adding trastuzumab to chemotherapy significantly reduced the risk of recurrence and improved survival rates.

Understanding trastuzumab helps you see why HER2 testing is now a standard part of breast cancer pathology — the result directly shapes the treatment plan. If you have been diagnosed with HER2-positive breast cancer, knowing what this therapy targets and why it was chosen can make your treatment feel less abstract and more purposeful.