HER2-Positive Breast Cancer

HER2-positive (HER2+) breast cancer is a fast-growing cancer. It happens when you have high levels of human epidermal growth factor receptor 2 (HER2). This is a protein that helps cancer cells grow and divide.

Experts estimate that 1 out of every 5 breast cancer cases are HER2-positive. Surgery and medication that targets the HER2 protein may cure it, especially if the cancer hasn’t spread beyond your breast.

Symptoms of HER2-positive breast cancer

HER2-positive breast cancer doesn’t cause distinct symptoms. You may have common breast cancer symptoms, including:

• Changes in the size, shape or contour of your breast
• Mass or lump in your breast, which may feel as small as a pea
• Changes in the texture or color of your breast skin
• Hardened area under your breast skin
• Nipple inversion
• Blood-stained or clear nipple discharge

HER2-positive breast cancer causes

This disease happens when the HER2 gene gains extra copies. This is called ERBB2 amplification. The HER2 gene makes HER2 proteins. All breast cells have HER2 proteins that manage breast cell growth and repair. The proteins make sure cells divide as needed to replace damaged or dying cells.

When the HER2 gene makes too many copies of itself, you start to have more abnormal genes. And this means you have more proteins telling breast cells to multiply. You don’t normally inherit the extra genetic copies from your biological parents. It happens after you’re born.

Genetic changes that lead to cancer may happen for several reasons. Experts don’t know why HER2 genes change. But they know there are some conditions that increase your overall risk of developing breast cancer.

Risk factors

HER2-positive risk factors are similar to those for other types of breast cancer. You may have an increased risk of if you:

• Have an inherited genetic change, like TP53, ATM or CHEK2
• Have a personal history of breast cancer or a condition like atypical ductal hyperplasia
• Start your period younger than usual
• Enter menopause later than usual
• Take hormone replacement therapy
• Have more than one alcoholic drink a day
• Have a history of radiation therapy for conditions like lymphoma
• Smoke
• Have obesity

Complications of HER2-positive breast cancer

The main complication is that cancer cells in your breast can quickly spread into your bloodstream and lymphatic system to reach your:

• Bones
• Brain
• Liver
• Lungs
• Lymph nodes that are far away from your breasts
• Skin

How doctors diagnose this condition

If tests show you have breast cancer, your healthcare provider will perform specific tests to check if it’s HER2-positive. These include:

• Immunohistochemistry (IHC): This test checks the HER2 protein levels in cancer cells.
• Fluorescence in situ hybridization (FISH): This test finds extra copies of the HER2 gene. Pathologists may use it to confirm IHC results.

How is HER2+ breast cancer treated?

Healthcare providers typically treat this cancer with a combination of surgery, targeted therapy and chemotherapy.

Surgery

Breast cancer surgery is an option if cancer hasn’t spread outside of your breast. You may have chemotherapy or HER2 targeted therapy before surgery to shrink the tumor.

Targeted therapy

These medications target the protein that drives HER2+ breast cancer. Some specific medications include:

• Antibody-drug conjugates (ADCs): A lab-made antibody attached to a chemotherapy medication delivers the chemotherapy directly to HER2 proteins on cancer cells. Examples include ado-trastuzumab emtansine (Kadcyla®) and fam-trastuzumab deruxtecan (ENHERTU®).
• Monoclonal antibody therapy: Lab-made antibodies attach to HER2 proteins. Trastuzumab (Herceptin®) and pertuzumab (Perjeta®) are examples.
• Tyrosine kinase inhibitors (TKIs): TKIs block the signals that HER2 proteins send to tell cancer cells to grow. Examples are lapatinib (Tykerb®) and neratinib (Nerlynx®).
• Hormone therapy: This is an option if you have HER2-positive breast cancer that’s also hormone-receptor positive.

A breast cancer diagnosis and treatment can be stressful. It’s normal to feel anxious or depressed. And you may feel like you should keep your worries to yourself instead of sharing them with a friend or family member. If you’re in this situation, ask your cancer care team about mental health and community-based support.

Recovery time

Your recovery will depend on your treatment. For example, it may take a few weeks to fully recover from breast cancer surgery. It may take less time to recover from cancer medication side effects.

Your cancer care team will explain how different treatments may affect you and how they’ll help manage them.

When should I see my healthcare provider?

You’ll see your provider regularly as you go through treatment. But you should contact them if you have trouble managing side effects.

Let your provider know about any changes in your breasts or overall health. For example, breast cancer that’s spread to your lungs may cause symptoms like chest pain, frequent chest infections, feeling short of breath or coughing up blood.

What are the survival rates for HER2+ breast cancer?

Survival rates are estimates of the percentage of people with a specific cancer diagnosis who are alive after a certain amount of time — usually five years after receiving the diagnosis.

HER2-positive breast cancer survival rates may vary depending on whether the cancer is hormone receptor-positive (HR+) or hormone receptor-negative (HR-). These are receptors on cells that can attach to hormones. About half of all HER2-positive breast cancers have these receptors.

In the U.S., the National Cancer Institute (NCI) organizes survival rates by stages: local, regional and distant. Here are the five-year relative survival rates for HER2+ breast cancer, according to NCI data:

• Local cancer (cancer hasn't spread beyond the breast): 99.5% for HR+/HER2+ breast cancer, and 97.8% for HR-/HER2+ breast cancer
• Regional cancer (cancer has spread to nearby lymph nodes): 91.5% for HR+/HER2+ breast cancer, and 86.4% for HR-/HER2+ breast cancer
• Distant cancer (cancer has spread to distant sites): 48.7% for HR+/HER2+ breast cancer, and 43.1% for HR-/HER2+ breast cancer

A relative survival rate shows whether a specific cancer shortens life. It compares the survival rates of people who have a specific type of cancer with the survival rates of those who don’t have cancer but are the same age, sex and race.

Survival rate information can be confusing and sometimes concerning. Keep in mind the rates are based on others’ experiences with HER+ breast cancer. What was true for them may not be true for you. Your experience may be very different. Ask your cancer care team to explain what survival rate data means in your situation.

Is HER2+ breast cancer curable?

Yes, treatment that gets rid of cancer before it spreads may cure it. But this type of breast cancer can come back even after successful treatment.

Can HER2-positive breast cancer be prevented?

No, you can’t prevent this disease. It happens when the HER2 gene changes. Researchers are still studying why that happens and are not sure how to specifically prevent HER2-positive breast cancer.

While you can’t prevent it, managing your breast health increases the chance that you or your healthcare provider will notice changes in your breasts that could be cancer. Here are some steps you can take:

• Ask your provider about breast cancer screenings.
• Do breast self-exams, which help you know what’s normal for you.
• Avoid alcohol.
• Don’t smoke.
• Maintain a healthy weight.
• Exercise consistently.
• Eat a Mediterranean, plant-rich diet.