HER2-positive breast cancers grow faster, spread more easily and tend to come back more often than other types of breast cancer. Medicines that target HER2 help many women with this type of breast cancer live longer.
When doctors analyze breast tissue from a biopsy, they look for molecular markers, such as the estrogen receptor, progesterone receptor and HER2. These findings can help determine a person’s treatment options.
Symptoms
A person’s chances of survival and the type of treatment she receives depend on the stage (how far the cancer has spread). In general, 5-year relative survival rates are based on how doctors classify cancer:
stage 0 — Ductal carcinoma in situ or noninvasive breast cancer that hasn’t reached the fatty tissue or lymph nodes;
stage 1 — Tumor larger than 2 centimeters that hasn’t spread beyond the lobe;
stage 2 — Cancer that has grown into nearby tissue but not to other organs in the chest or axillary (underarm) lymph nodes; and
stage 3 — Cancer that has spread to other areas of the body.
If a person’s HER2-positive breast cancers is stage 3 or higher, she may be given chemotherapy drugs and trastuzumab. Trastuzumab targets the HER2 protein and interferes with its ability to grow and divide. Many people who get HER2-positive breast cancer go into remission with this treatment.
If a patient’s cancer recurs or progresses, her doctor needs to do a new biopsy and re-confirm the tumor’s HER2 status. This information helps the doctor choose the best treatment plan for her. It also helps the doctor know whether she should give patients “maintenance” antibody therapy to keep the cancer from growing or spreading again.
Diagnosis
The HER2 gene (ERBB2) makes proteins that help cells grow and repair themselves. If a breast cancer tumor has extra copies of the HER2 gene or makes too much HER2 protein, it is considered HER2-positive and can spread faster than normal breast cancer cells. Doctors check HER2 status in all breast cancer tumors at diagnosis. The HER2 is tested with a biopsy. This involves a small tissue sample from the cancer that will be examined for the presence or absence of the HER2 protein or gene.
These breast cancers spread and grow faster than others, so drugs targeting the HER2 gene are often used. These drugs are known as HER2-directed therapy and are very effective at treating HER2-positive cancers.
Most HER2-positive breast cancers are detected early and treated using neoadjuvant therapy before surgery, followed by HER2-directed treatment after surgery. HER2-directed treatment is also used to treat metastatic HER2-positive cancers that have spread to other body parts.
It’s important to let your doctor know if you have new symptoms so they can evaluate whether they are due to cancer or if it has returned. If your cancer is metastatic, treatment options may be limited.
Treatment
All breast cancers are different, and your care team needs to know the details of your specific disease. Your doctor may test your tumor for HER2 status, which can tell them whether your cancer is likely to grow quickly and spread or respond to certain treatments.
HER2 is a protein found on all cells’ surface and controls normal cell growth. Some tumors have extra copies of the gene that makes HER2, which causes them to grow faster than they should. HER2-positive tumors tend to be more aggressive than other types of breast cancer and have higher rates of recurrence (coming back).
Your doctor will use a biopsy to find out if your cancer has HER2 levels that are too high. They will also ask about other characteristics of your cancer, such as hormone receptor status. If the results of your IHC test are equivocal or borderline (2+), your doctor will do another test to confirm HER2 status before making treatment recommendations.
Once doctors know your HER2 and hormone receptor status, they can recommend treatment options that are likely to be effective. These treatments include chemotherapy (drugs that kill cancer cells) and radiation therapy (targeted energy directed at the tumor).
Side Effects
The treatment of breast cancer depends on several factors. These include the stage at which it is diagnosed and whether or not the cancer has spread to nearby tissues or lymph nodes. The outlook varies according to age. Younger women have a poorer prognosis.
A HER2-positive result means the tests have shown high levels of a particular protein called human epidermal growth factor receptor 2 (HER2). This gene can be overactive, causing cancerous cells to grow quickly. Breast cancers with high HER2 levels are aggressive and spread more rapidly than other types.
Doctors can usually cure HER2-positive breast cancers confined to the breast and nearby lymph nodes. However, the disease can return, and it is important to follow up regularly with healthcare providers to look for new tumors or signs that the cancer is spreading.
The good news is that advances in treatment are improving the outlook for patients with HER2-positive breast cancer. For example, medicines that target the HER2 protein can help reduce cancer growth and the risk of the cancer spreading. The drugs can also be used alone or with other treatments, such as surgery and radiation therapy. Research continues into ways to understand HER2-positive breast cancers better and create more effective therapies.
