HER-2 positive (Human Epidermal Growth Receptor 2) breast cancers make up about 15-20% of invasive breast cancers seen in the United States. HER-2 positive breast cancers have an abundance of protein molecules on their surface, called receptors. When these receptors are stimulated, they in turn activate genes in the cancer cell nucleus called oncogenes. These oncogenes produce proteins that act to stimulate the breast cancer to grow. This is referred to as overexpression or amplification of the gene.
HER-2 positive breast cancers can be treated with very effective drugs that go to a specific target, the HER-2 receptor. When these medications attach to the HER-2 positive breast cancer cells, they are able to destroy them. The two current medications that are used to treat HER-2 positive breast cancer are Trastuzamab (trade name Herceptin) and Pertuzamab (trade name Perjeta). The combination of chemotherapy with Herceptin and Perjeta is phenomenal and has tremendous success in killing HER-2 positive breast cancer.
Because Herceptin and Perjeta are so effective in treating HER-2 positive breast cancers they are often referred to as “silver bullet drugs”. A “silver bullet drug” will only go to one type of cell. These “silver bullets” will then concentrate on their intended target and then destroy that cell. Normal cells will not be affected. The “silver bullet drugs” for HER-2 positive breast cancer are Herceptin and Perjeta, wonder drugs of this new age in fighting cancer using targeted therapies specific to the individual’s breast cancer biology.
Because long-term survival in breast cancer patients is dependent on preventing metastatic breast cancer (breast cancer that has spread outside the breast and lymph nodes under the arm), many breast cancers that have aggressive biology are being treated by chemotherapy as the first form of treatment. This is referred to as “neoadjuvant” therapy (in contrast, “adjuvant” therapy refers to chemotherapy given after surgery). HER-2 positive breast cancers are often felt to be aggressive enough to warrant chemotherapy before any surgery. The targeted drugs are systemic therapies that go throughout the body and kill cancer cells that may be too few in number to detect with standard imaging and lab tests, but may become problematic with time. Surgery will only treat the breast and lymph nodes under the arm. Systemic therapy will treat the breast and axillary lymph nodes as well as the entire body.
If you have been diagnosed with breast cancer, ask your surgeon if your breast cancer is HER-2 positive. If your breast cancer is HER-2 positive, you will need to meet with a medical oncologist prior to surgery for your breast cancer to see if you could benefit from targeted systemic therapy prior to surgery.