For a woman whose tumor contains a specific tumor marker called HER2 (human epidermal growth receptor 2), physicians may recommend a therapy called trastuzumab (Herceptin®) after initial treatment. 

How does anti-HER2 therapy work?

Each healthy breast cell contains two copies of the HER2 gene. This gene is intended to help cells grow normally. If a breast cell has too many copies of the HER2 gene along with too much of the HER2 protein on the cell surface, the cell may grow out of control and become a tumor.

Trastuzumab (Herceptin®) blocks the function of this protein in tumors whose HER2 gene is stuck on overdrive. Studies of the drug show that can reduce by half the risk of recurrence and death in patients with these early stage tumors.

How is anti-HER2 therapy administered?

Treatment is administrated intravenously weekly or every three weeks for up to a year after active treatment is complete. There are often very few side effects with trastuzumab (Herceptin®) and it is usually well-tolerated by patients. Patients will not lose any more hair and are able to go back to work. A small number of patients may develop temporary or permanent heart weakness with this treatment.

Your doctor may order an echocardiogram (sonogram of the heart) or a MUGA (nuclear medicine) scan every few months to monitor your heart function while taking this drug.