Ryland Gore, MD, explains some of the specific challenges and treatments for HER2-positive breast cancer.
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HER2-positive breast cancer is a type of breast cancer that grows and spreads quickly. If you have HER2-positive breast cancer, it means your cancer cells contain high levels of a protein called human epidermal growth factor receptor 2 (HER2).
Normally, HER2 helps your healthy breast cells grow and divide. But too much HER2 can trigger cells to grow out of control. Between 15 and 20 percent of all breast cancers are HER2-positive.
Though HER2-positive breast cancer is aggressive, treating it before it spreads can result in a cure.
Breast cancer may cause any of these symptoms. Some people experience no symptoms at all.
Breast skin that’s red, dimpled, thickened, flaky, or dry
Nipples that are pulled inward
Nipple discharge
Swollen lymph nodes
Sometimes there are no signs or symptoms at all, and breast cancer is detected on a screening mammogram.
Causes and Risk Factors of HER2-Positive Breast Cancer
HER2-positive breast cancer happens when the HER2 gene in your DNA mutates (changes) and makes extra copies of the genes that make the HER2 protein. Having more HER2 proteins causes breast cells to divide and grow too quickly, leading to the growth of cancerous tumors.
Researchers aren’t sure exactly what causes HER2 genes to mutate. Genetics, lifestyle habits, and environmental factors may all play a role.
Some factors that increase your risk of breast cancer, including HER2-positive breast cancer, include:
Being female
Giving birth for the first time after age 30
Drinking heavily
Using tobacco products
Being overweight or having obesity
Living a sedentary lifestyle
Having previous radiation therapy to the chest
How Is HER2-Positive Breast Cancer Diagnosed?
Your doctor will perform a biopsy to diagnose breast cancer. This involves removing a sample of tissue from your tumor and sending it to a laboratory for analysis.
Among the tests that are done in the lab are those used to see if and how much HER2 sits on the surface of the cancer cells. A doctor who is trained to analyze cells under a microscope will perform either an immunohistochemistry (IHC) or a fluorescence in situ hybridization (FISH) test, and sometimes both.
IHC is a staining process that can show whether cancer cells have HER2 proteins on their surface. FISH looks for additional copies of the HER2 gene in breast cancer cells.
It’s not known if one of these tests is better than the other, but FISH generally costs more and takes longer to get the results back. This is why IHC is often performed first.
An IHC score of 1+ is considered HER2-negative because these cancers usually don’t respond to treatments that target HER2, but new research shows that targeted drugs might help in cases where the cancer has metastasized (spread to distant areas). These are also called HER2-low breast cancers.
If the IHC score is 2+, this is called “equivocal,” and means that the HER2 status of your cancer is unclear. Doctors will perform a FISH test to clarify the result. If the FISH test result is negative, this is HER2-low breast cancer. This means the tumor contains a low amount of HER2, but not enough to be considered HER2-positive. If the FISH test result is positive, the cancer is HER2-positive.
An IHC score of 3+ is HER2-positive breast cancer.
If breast cancer comes back or spreads, your HER2 status should be retested because it can change.
Prognosis for HER2-Positive Breast Cancer
In general, HER2-positive breast cancer tends to grow faster and spread earlier than other types of cancer — and come back. However, it responds well to medicines that target HER2 proteins.
Your prognosis will depend on many factors, including your overall health, the stage of your cancer, and the treatments you receive. The survival rate for HER2-positive breast cancer also depends on whether the cancer feeds off the hormones estrogen and progesterone (hormone receptor–positive breast cancer) or doesn’t need these hormones to grow (hormone receptor–negative breast cancer).
The five-year survival rate for HER2-positive breast cancers that are also hormone receptor–positive is:
99 percent for cancers that haven’t spread outside the breast
90 percent for cancers that have spread to lymph nodes and nearby tissue
46 percent for cancers that have spread to distant areas of the body
The five-year survival rate for HER2-positive breast cancers that are hormone receptor–negative is:
97 percent for cancers that haven’t spread outside the breast
84 percent for cancers that have spread to lymph nodes and nearby tissue
40 percent for cancers that have spread to distant areas of the body
While these survival rates may help you better understand your outlook, it’s important to remember that they are only estimates. They can’t predict what will happen in your particular situation. Your doctor will be able to tell you more about your prognosis based on other factors that affect your overall health.
Treatment and Medication Options for HER2-Positive Breast Cancer
Treatment for HER2-positve breast cancer will depend on the stage of your cancer, the tumor’s hormone status, the size of your tumor, your overall health, and other factors. Sometimes treatments are combined for a better effect.
Surgery
Surgery is an option for many patients with breast cancer. Depending on the stage of your breast cancer, chemotherapy and/or targeted therapy may be given before surgery. Doctors may perform:
Lumpectomy With this procedure, only the tumor and some surrounding tissue are removed.
Mastectomy The entire breast is surgically removed, sometimes with other nearby tissues.
Chemotherapy
Chemotherapy uses medicines to destroy cancer cells in your body. Chemo can be given as an intravenous (IV) infusion directly into your bloodstream or taken by mouth as a pill. It may be administered before or after breast cancer surgery. Chemo is sometimes used in combination with targeted treatments.
Commonly used chemotherapy drugs for breast cancer include:
Taxanes, such as paclitaxel (Taxol) and docetaxel (Taxotere)
5-fluorouracil (5-FU) or capecitabine (Xeloda)
Anthracyclines, such as doxorubicin (Adriamycin), liposomal doxorubicin (Doxil), and epirubicin (Ellence)
Platinum agents, such as cisplatin (Platinol) and carboplatin
Targeted Therapy
Targeted medicines are drugs that target the HER2 protein. There are different types of targeted therapies, including monoclonal antibodies, antibody-drug conjugates, and kinase inhibitors.
Monoclonal Antibodies
These medicines attach to the HER2 protein on cancer cells and prevent the cancer cells from growing. They are typically used with chemo and sometimes combined with other monoclonal antibodies. Some examples of monoclonal antibodies are:
Trastuzumab (Herceptin) This drug can be used alone or with chemo, before or after surgery. Trastuzumab is given as an IV.
Trastuzumab and Hyaluronidase Injection (Herceptin Hylecta) This is another form of trastuzumab that’s given as a shot under the skin.
Pertuzumab (Perjeta) This monoclonal antibody can be used before or after surgery to treat early HER2-positive breast cancer as well as metastatic HER2-positive breast cancer. Pertuzumab is administered as an IV and can be given along with trastuzumab and chemo.
Trastuzumab, Pertuzumab, and Hyaluronidase Injection (Phesgo) This combination of drugs is used for both early and metastatic HER2-positive breast cancers. It’s given as a shot under the skin, and may be used with other medications.
Margetuximab (Margenza) This medication is used to treat metastatic HER2-positive breast cancer that hasn’t responded to at least two other targeted therapies. Margetuximab is given as an IV and can be used along with chemo.
Antibody-Drug Conjugates
An antibody-drug conjugate is a monoclonal antibody that is linked to a chemo drug. They attach to the HER2 protein on cancer cells, which helps deliver the chemo directly to the bad cells.
Antibody-drug conjugates used for HER2-positive breast cancer include:
Ado-Trastuzumab Emtansine (Kadcyla) Emtansine is the chemo drug connected to this antibody-drug conjugate. Ado-trastuzumab emtansine can be used by itself for early-stage HER2-positive breast cancer after surgery or for metastatic HER2-positive breast cancer in those who have previously received trastuzumab and chemo. This drug is administered as an IV.
Fam-Trastuzumab Deruxtecan (Enhertu) Deruxtecan is the chemo drug connected to this antibody-drug conjugate. Fam-trastuzumab deruxtecan is used for HER2-positive or HER2-low breast cancer that has metastasized or can’t be removed with surgery, usually after another therapy has been tried. This drug is given as an IV.
Kinase Inhibitors
Kinases are proteins that send signals to the cell. HER2 is a type of kinase that tells the cell to grow. Kinase inhibitors block kinases so these signals can’t be relayed. They are usually taken as a pill and may be given with other targeted medicines or chemotherapy. Some examples of kinase inhibitors are:
Lapatinib (Tykerb), which is used for metastatic breast cancer
Neratinib (Nerlynx), used for early-stage breast cancer after previous treatment with trastuzumab, or for metastatic breast cancer, usually after at least two other targeted therapies have been tried
Tucatinib (Tukysa), which is used to treat metastatic breast cancer after at least one other targeted therapy has been tried
Hormone Therapy
If your breast cancer feeds on the hormones estrogen and progesterone (your cancer is also hormone receptor–positive), you may also receive hormone therapy. This treatment blocks your body’s ability to produce hormones, or it acts on how the hormones affect breast cancer cells. Some examples are tamoxifen (Nolvadex) and letrozole (Femara).
Radiation
Radiation therapy involves delivering energy rays or particles to destroy cancer cells. It’s often used after surgery to get rid of any remaining cancer cells.
Clinical Trials
Clinical trials are studies that are done to test the safety and effectiveness of new treatments. Some people with HER2-positive breast cancer may choose to participate in a trial to try a new treatment that isn’t yet available to the public.
Questions to Ask Your Doctor
What stage is my cancer?
Is my breast cancer hormone receptor–positive or hormone receptor–negative?
What treatments do you recommend and why?
What are the potential side effects of the treatments?
What is my prognosis?
How does my HER2 and hormone status affect my outlook?
Is a clinical trial a good idea? How can I find out more?
Complementary and Integrative Therapies
Complementary and integrative treatments won’t provide a cure for breast cancer, but they may help you feel better and lessen treatment side effects.
Some popular complementary therapies include:
Exercise or physical therapy
Yoga or tai chi
Acupuncture
Massage
Music therapy
Mindfulness meditation
Journaling
Aromatherapy
Hypnosis
Prevention of HER2-Positive Breast Cancer
There’s no way to completely prevent breast cancer, but you may be able to lower your risk of the disease by adopting these lifestyle habits:
Don’t consume alcohol, or avoid daily use of alcohol.
Exercise for at least 30 minutes on most days of the week.
Maintain a healthy weight.
Limit the use of combination hormone replacement therapy (HRT) during menopause.
Avoid radiation therapy to the chest area if you can.
Complications of HER2-Positive Breast Cancer
When HER2-positive breast cancer metastasizes in the body, it can cause complications. For example:
If the disease spreads to the brain, you might notice headaches; speech, vision, or memory problems; or behavior changes.
If it moves to the bones, you could have bone pain, fractures, or swelling.
Cancer that affects the liver can cause jaundice, stomach pain, and itchy skin.
Metastasis to the lung might result in chest pain, shortness of breath, or a cough that doesn’t go away.
Other complications caused by cancer treatments may include:
Bleeding
Fatigue
Hair loss
Infection
Infertility
Lymphedema (swelling that occurs due to a buildup of lymph fluid under the skin)
Memory problems
Menopause symptoms
Nausea, diarrhea, or vomiting
Nerve damage
Scarring
Sexual problems
Research and Statistics: Who Has HER2-Positive Breast Cancer?
According to the American Cancer Society, 310,720 new cases of breast cancer are diagnosed each year, and about 1 of every 5 breast cancers are HER2-positive.
HER2-positive breast cancer is more likely to affect younger women than other forms of breast cancer. Men and people assigned male at birth rarely develop HER2-positive breast cancer.
Disparities and Inequities in HER2-Positive Breast Cancer
Though white women have the highest overall prevalence of breast cancer, Black women tend to have worse outcomes. In fact, studies show Black women have the lowest five-year relative survival rate compared to other racial groups for every stage and every subtype of breast cancer, including HER2-positive breast cancer.
The reasons for this disparity are complicated, but some experts believe inequalities in care, lifestyle habits, environmental factors, and genetics may all play a role.
Related Conditions
Some conditions that are closely related to HER2-positive breast cancer include:
Ductal Carcinoma In Situ (DCIS) With DCIS, the cells that line the milk ducts in your breast start to change and look like cancerous cells.
Support for HER2-Positive Breast Cancer
Finding support can help you cope with your cancer diagnosis. You might want to connect with other survivors via an online or in-person support group. Or some people benefit from talking to a mental healthcare professional.
Organizations that provide resources and support for people with breast cancer include:
American Cancer Society The American Cancer Society Reach to Recovery program connects people diagnosed with breast cancer with trained volunteers who are breast cancer survivors.
Breast Cancer Now You can speak to a nurse, join a course, or meet other people facing similar challenges with breast cancer.
Breastcancer.org Find breast cancer education, research news, and a community of supporters for people with breast cancer and their caretakers.
CancerCare Free, professional support services, including counseling, are offered for people affected by breast cancer.
National Breast Cancer Foundation Find breast cancer education, patient navigation, and support services through this national organization.
Susan G. Komen Trained oncology social workers are available to speak with you through the foundation’s helpline.
The Takeaway
With HER2-positive breast cancer, cancer cells contain high levels of the HER2 protein. This type of breast cancer typically grows and spreads quickly. However, targeted drugs that focus on the HER2 protein are often effective treatment options. If HER2-positive breast cancer is detected and treated early, the chance for a cure is possible.
Common Questions & Answers
Where does HER2-positive breast cancer come from?
HER-2 positive breast cancer happens when a gene mutation causes breast cells to make too much of the HER2 protein. This triggers cancer cells to grow out of control.
What increases the risk of HER2-positive breast cancer?
Some risk factors for HER2-positive breast cancer include being female, giving birth for the first time after age 30, consuming alcohol or using tobacco, being overweight, and having had radiation therapy to the chest.
Where does the HER2 protein come from?
The HER2 protein sits on breast cells. Normally, it helps them grow and divide. But too much HER2 can make cells grow and divide uncontrollably, leading to tumors.
Who gets HER2-positive breast cancer?
HER2-positive breast cancer is more likely to affect younger women than others. Men rarely develop this type of breast cancer.
Lisa Curcio, MD, is a board-certified general surgeon and a fellowship-trained surgical oncologist. She is currently the medical director of breast surgery at Northern Dutchess Hospital in Rhinebeck, New York. Dr. Curcio attended George Washington University Medical School in Washington, D.C., where she also completed a residency in general surgery. She was invited to fellowship training in cancer surgery at City of Hope National Medical Center in Duarte, California. She was the recipient of the competitive U.S. Air Force Health Professions Scholarship Program. During her military commitment, Dr. Curcio served in the military as chief surgical oncologist at Keesler Medical Center in Biloxi, Mississippi.
From 2003 to 2004, she served as program director for Susan G. Komen in Orange County and remains involved with Komen outreach efforts. She was on the board of Kids Konnected, a nonprofit that helps children of cancer patients deal with the emotional fallout of a cancer diagnosis. Currently, she is on the board at Miles of Hope Breast Cancer Foundation, an organization dedicated to providing support services for people affected by breast cancer in New York's Hudson Valley. Dr. Curcio also has a strong background in breast cancer research, having contributed to dozens of peer-reviewed articles. She is currently a member of the Alpha Investigational Review Board.
Her practice includes benign and malignant breast diagnoses. Dr. Curcio was diagnosed with breast cancer at the age of 37. Although her fellowship training was in surgical oncology, this experience motivated her to provide compassionate, high level breast care and to focus on breast surgery.
Dr. Curcio is passionate about treating the patient and individualizing the care plan to their specific needs. Dr. Curcio strongly believes that cancer care must include lifestyle changes to focus on healthier habits to reduce future events. Her practice also focuses on breast cancer risk reduction, education, and access to genetic testing for patients with a family history of breast cancer.
Julie Marks is a freelance writer with more than 20 years of experience covering health, lifestyle, and science topics. In addition to writing for Everyday Health, her work has been featured in WebMD, SELF, Healthline, A&E, Psych Central, Verywell Health, and more. Her goal is to compose helpful articles that readers can easily understand and use to improve their well-being. She is passionate about healthy living and delivering important medical information through her writing.
Prior to her freelance career, Marks was a supervising producer of medical programming for Ivanhoe Broadcast News. She is a Telly award winner and Freddie award finalist. When she’s not writing, she enjoys spending time with her husband and four children, traveling, and cheering on the UCF Knights.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
