HER2 positive metastatic breast cancer occurs when cancer cells have a higher level of the protein human epidermal growth factor receptor 2 (HER2). Higher levels of the HER2 protein can be troublesome because the protein helps breast cancer cells grow, multiply, and repair damage. If there is too much HER2 protein present, cancer may develop. About 20 percent of breast cancer cases are HER2 positive. HER2 positive metastatic breast cancer is cancer that has spread from the breast to other parts of the body.
Although doctors are not certain on why HER2-positive breast cancer occurs, they do know that the HER2 gene is hereditary, which means it can be passed down from parents to children. This is one reason why patients and their family members should get tested to see if they are HER2 positive or negative so that they can be informed about their potential risk of developing breast cancer.
HER2 Positive Metastatic Breast Cancer Symptoms
HER2 positive metastatic breast cancer symptoms are similar to all types of breast cancer. The most common sign is a small, hard lump in the breast. Other symptoms include:
- Swelling and tenderness of the breast
- Pain in the breast or nipple
- Redness or thickening in the breast or nipple
- Unusual nipple discharge
- Irritated or dimpled breast skin
Getting a HER2 Positive Diagnosis
Once a breast cancer diagnosis has been determined, doctors will do tests to determine if the presence of HER2 is positive or negative. Tests required to determine this include:
- Immunohistochemistry (IHC) test: measures how many HER2 proteins are on breast cancer cells.
- Fluorescent in situ hybridization (FISH) test: looks for extra copies of the HER2 gene, which makes the HER2 protein.
Treatment for HER2 positive metastatic breast cancer often involves targeted therapy. Targeted therapy targets specific tissues, genes, or proteins that play a part in cancer growth. Targeted therapy for HER2 positive breast cancer targets the HER2 positive protein and avoids healthy cells, stopping the overgrowth of cancer cells, which is why this therapy is often more effective than standard treatments such as surgery, chemotherapy, radiation, and hormone therapy. Clinical trials are also an option for HER2+ metastatic breast cancer.