A breast cancer diagnosis can be devastating for any patient. But there is hope — and treatment — for many. In the United States, women with early-stage (localized) her2 positive breast cancer have a 5-year survival rate of 98.8%, and this is even higher if the cancer has not spread to other parts of the body. HER2-positive breast cancer is a type of fast-growing tumor that produces too much of the HER2 protein. This protein is present on the surface of breast cells and relays growth signals to other parts of the cell.
All healthy cells have HER2 receptors on their surfaces, but when cancer cells produce too much of the protein, they grow more rapidly. When doctors biopsy a breast tumor, they look for the presence of HER2 genes in the tissue sample. If the tumor is HER2-positive, they can identify specific targeted treatments that are very effective in treating this type of cancer.
HER2 testing is done using two different tests. One, called immunohistochemistry (IHC), uses antibodies that detect HER2 protein in the tissue. The other, fluorescent in situ hybridization (FISH), looks for extra copies of the HER2 gene. If the IHC results are inconclusive, a FISH test is typically performed to provide more definitive results.
Breast cancers are classified into four molecular subtypes based on the proteins they express: hormone receptor-positive (HR+)/Human epidermal growth factor receptor 2 (HER2)-negative (Luminal A); HR-/HER2-positive (Luminal B); HR-/HER2-negative (triple negative); and HER2-/ER-positive (HER2+/ER+). The survival rates vary depending on the molecular subtype and stage of the tumor.
If a patient has a HER2-positive tumor, it’s important that she receive care from a center that regularly treats this type of cancer. At MD Anderson, we use a combination of surgery, chemotherapy and a single antibody targeting the HER2 protein known as trastuzumab (Herceptin).
In addition to testing for HER2, it’s important that a patient who is diagnosed with a breast tumor undergoes regular screening with a clinical breast exam and mammograms. If a lump or other abnormality is found, the patient should see her doctor immediately and follow her to determine whether it’s benign or malignant.
A symptom of breast cancer that may indicate the need for further evaluation is a lump that feels different from other parts of the breast. Patients with breast cancer should also seek medical attention if they notice any of the other common symptoms of the disease, including persistent or worsening pain or swelling of the breasts or armpits.
During the diagnostic process, the pathologist who examines a biopsy or surgical specimen will report on several features of the tumor, including its HER2 status. Historically, HER2-positive cancers have been associated with poor outcomes and lower survival rates than other breast cancer subtypes. However, with the introduction of HER2-targeted therapies such as Herceptin, HER2-positive cancers have become a highly treatable and manageable disease. In fact, five-year survival rates for HER2-positive breast cancer have surpassed 90 percent for patients treated with a combination of chemotherapy and trastuzumab.
