What is HER2-positive breast cancer?

HER2-positive breast cancer is a type of breast cancer that has higher than normal levels of a protein called hormone epidermal growth factor receptor 2 (HER2). This protein makes the cancer cells grow faster than cancers that are HER2-negative. Although HER2-positive breast cancer can grow quickly, treatments that target the HER2 protein are very effective.

About 20 percent of people with breast cancer have HER2-positive breast cancer. If you have breast cancer, your doctor may suggest HER2 testing to see if your cancer is HER2-positive. The results will help guide your treatment.

What are the symptoms of HER2-positive breast cancer?

The most common symptom is a lump in the breast. Other symptoms may include:

  • A change in the shape of the breast
  • Discharge (not breastmilk) from the nipple
  • Pain in the breast or nipple
  • A dimpling in the skin on the breast
  • In many cases, breast cancer is found on a mammogram test

How is HER2-positive breast cancer treated?

Treatment for HER2-positive breast cancer depends on what stage the cancer is at and if it has spread to other parts of the body. Treatments may include some or all of the following:

  • Surgery to remove the tumor (lumpectomy) or, in some cases, the entire breast (mastectomy)
  • Targeted therapy drugs that attack the HER2 proteins and help stop the cancer cells from growing
  • Chemotherapy to shrink the tumor or help kill any cancer cells that have spread to other parts of your body
  • Radiation therapy to help destroy any cancer cells left in your breast

What are the risk factors HER2-positive breast cancer?

Risk factors for HER2-postitve breast cancer are generally the same as for other types of breast cancer. They include:

  • Having certain genes, such as BRAC1 and BRAC2, that can run in families
  • Being over age 50
  • Having dense breasts
  • Starting menstrual periods before age 12 or menopause after age 55
  • Having a family history of breast cancer or ovarian cancer
  • Being overweight after menopause
  • Taking some types of hormone replacement therapy or birth control pills
  • Drinking alcohol
  • Not being active

Departments and Programs Who Treat This Condition


Breast Cancer Program

BMC’s Breast Health Program provides collaborative, multidisciplinary care to patients with breast cancer from the first consultation through treatment and follow-up visits.