The primary drug used for breast cancer is trastuzumab, which lowers the risk of tumors coming back in women with HER2-positive breast cancer.

Trastuzumab attaches to the HER2 receptor of these cells and makes the cancer cell stop dividing and multiplying. It is normally given every 3 weeks over a 1-year period and can be given together with chemotherapy or alone.

Trastuzumab can be given through a vein (as with chemotherapy) or injected into the skin.

After you receive trastuzumab, you must wait for 1 to 2 hours to make sure that you do not develop any side effects.

Over the year you are taking trastuzumab, your doctor will monitor the way your heart is functioning to avoid any possible damage.

Other targeted therapies used for HER-positive tumors are pertuzumab and TDM-1.