HER2-Positive Breast Cancer: Symptoms, Causes & Treatment

Breast cancer is a disease that affects millions of women worldwide. It develops when breast cells start growing uncontrollably and form tumors that can invade nearby tissues or spread to other parts of the body. Breast cancer comes in many forms, and some types grow faster or behave more aggressively than others.

One such type is HER2-positive breast cancer. Let’s first understand what it is and how it grows.

What is HER2-Positive Breast Cancer?

HER2-positive breast cancer is an aggressive type of breast cancer that spreads rapidly. This form develops when the HER2 protein is overproduced. HER2 stands for Human Epidermal Growth Factor Receptor 2 (a protein on breast cells that normally helps them grow and divide).

You can think of HER2 as a switch that tells cells when to multiply. In HER2-positive cancer, the switch stays in the “on” position. As a result, the cells keep dividing more quickly than they should. This leads to faster tumor growth and, in some cases, a higher chance of spreading if treatment is delayed.

Difference Between HER2‑Positive and HER2‑Negative Breast Cancer

HER2‑positive breast cancer has high levels of the HER2 protein, which makes the cancer grow faster and increases the risk of spreading. It can be treated with therapies that specifically target the HER2 protein.

In contrast, HER2‑negative breast cancer has normal or low HER2 levels, tends to grow more slowly, and does not respond to HER2-targeted treatments.

How Common is HER2-Positive Breast Cancer?

HER2-positive breast cancer is an important subtype that accounts for 15 to 20% of all breast cancers. This means that about one in every five breast cancer cases involves tumors where the HER2 protein is overproduced.

Because the HER2 protein encourages faster cell growth, these cancers tend to be more aggressive than other breast cancer types. It can occur in women of any age, though some studies suggest it may be slightly more common in younger women. Male cases are very rare, but they can happen.

HER2-Positive Breast Cancer Symptoms

HER2-positive breast cancer often presents symptoms similar to other types of breast cancer. Still, because it tends to grow faster, these signs may appear more quickly or become noticeable in a shorter period.

Common symptoms may include:

• Changes in breast size or shape
• Swelling or thickening of part of the breast
• Skin changes, such as redness, dimpling, or puckering
• Nipple changes, including discharge, inversion, or pain
• A lump in the breast or underarm that feels firm or unusual
• Pain or tenderness in the breast (less common but possible)

In some cases, HER2-positive breast cancer can spread (metastasize) to other parts of the body. When this happens, symptoms may depend on where it has spread.

Causes and Risk Factors

HER2-positive breast cancer develops when certain changes in breast cells cause them to grow faster than normal. Knowing the underlying causes and risk factors can help you understand your risk and take proactive steps for early detection.

What Causes HER2-Positive Breast Cancer?

HER2-positive breast cancer is caused by changes in the HER2 gene, which is responsible for making the HER2 protein. Normally, this protein helps breast cells grow and divide in a controlled way.

However, in HER2-positive cancer, the HER2 gene becomes amplified or overexpressed, meaning the cells produce too many copies of the HER2 protein. This overproduction causes cells to divide rapidly and uncontrollably, which leads to the formation of a tumor.

Is HER2 Positive Breast Cancer Hereditary?

In most cases, HER2-positive breast cancer is not inherited. The gene changes usually happen in the breast cells during a person’s lifetime rather than being passed down from parents. However, rare genetic mutations or DNA damage from environmental factors may increase the risk.

Risk Factors

Certain factors can increase the likelihood of developing breast cancer in general, including this subtype. Having one or more risk factors does not mean you will definitely develop cancer. It only means your risk may be higher.

• Age remains one of the biggest factors. Breast cancer risk increases as you grow older.
• Family history also matters. If close relatives such as a mother, sister, or daughter had breast cancer, your chances may increase.
• Hormonal factors play a role, too. Early menstruation, late menopause, or long-term hormone therapy can slightly increase risk because of longer estrogen exposure.
• Lack of physical activity, excess body weight after menopause, smoking, and alcohol use can all influence overall breast cancer risk.
• Radiation exposure to the chest earlier in life can increase the chances as well. This includes radiation treatment during childhood or young adulthood.

Understanding these risks helps you stay alert. Regular screening and awareness can lead to earlier detection and better outcomes.

Diagnosis of HER2-Positive Breast Cancer

Doctors use several steps to diagnose HER2-positive breast cancer. The process usually begins when a lump, symptom, or screening test raises concern.

Imaging: Mammography often serves as the first test. It can detect abnormal breast tissue before symptoms appear. Ultrasound or MRI may follow if more details are needed.

Biopsy: If imaging shows something suspicious, a biopsy is performed to remove a small tissue sample from the breast. The sample is carefully analyzed to confirm cancer and determine HER2 status. This usually includes:

• Microscopic Examination: Pathologists study the tissue to confirm whether cancer cells are present.
• Immunohistochemistry (IHC) Test: Measures how much HER2 protein is present on the surface of cancer cells.
• Fluorescence in Situ Hybridization (FISH) Test: Checks for extra copies of the HER2 gene, which can indicate a HER2-positive cancer.

Seeking medical help early is very important. Early testing helps doctors identify whether the cancer is HER2-positive and choose the most effective treatment. The sooner you get clear answers, the better your chances of managing the condition successfully.

Treatment for HER2-Positive Breast Cancer

Treating HER2-positive breast cancer requires a carefully planned approach. Treatment often combines several strategies.

Surgery

Surgery is usually the first step for many patients, as it physically removes the tumor from the breast. The type of surgery depends on the tumor size, location, and whether the cancer has spread to lymph nodes:

• Lumpectomy (breast-conserving surgery): Only the tumor and a small margin of surrounding tissue are removed. This allows the breast to be mostly preserved. Surgery is usually followed by radiation therapy to eliminate any remaining cancer cells in the breast.
• Mastectomy: In cases of larger tumors, multiple areas of cancer, or when preserving the breast is not safe, the entire breast may be removed.

Systemic Therapy

Systemic therapy treats cancer cells throughout the body, including those too small to detect. For HER2-positive breast cancer, this approach is crucial because of the aggressive nature of the disease.

1: Chemotherapy

This treatment uses strong medications to destroy fast-growing cancer cells. Chemotherapy may be given before surgery to shrink tumors or after surgery to reduce the risk of cancer returning.

2: Targeted Therapy

HER2-positive tumors respond well to treatments that specifically attack HER2 protein signals. This approach slows or stops tumor growth while limiting damage to healthy cells.

Types of treatment include:

• Monoclonal Antibodies: These attach to the HER2 proteins on the surface of cancer cells. By doing so, they block the growth signals and also help the immune system identify and attack the tumor.
• Antibody-Drug Conjugates: These therapies first recognize and attach to the HER2-positive cancer cells. Once attached, they deliver a cancer-fighting agent directly into the tumor, minimizing harm to healthy tissue.
• Tyrosine Kinase Inhibitors: These work inside the cancer cells. They block the signals that drive rapid growth, which slows tumor progression and improves the effectiveness of other treatments.

Hormone Therapy

If the cancer also depends on hormones to grow, hormone-blocking treatments may be added to prevent recurrence.

Often, these therapies are combined in a personalized plan. Doctors consider tumor size, stage, spread, and overall health to select the most effective combination while reducing side effects.

Radiation Therapy

Radiation therapy uses high-energy rays to kill any remaining cancer cells after surgery. It is typically recommended after lumpectomy and sometimes after mastectomy. Radiation lowers the risk of local recurrence and is carefully targeted to minimize exposure to surrounding healthy tissues.

HER2‑Positive Breast Cancer Prognosis, Survival Rate, & Life Expectancy

Prognosis

The prognosis of HER2‑positive breast cancer has improved dramatically over the past two decades. Thanks to modern therapies, many patients respond very well to treatment, even when cancer is aggressive.

Life Expectancy

The life expectancy for someone with HER2-positive breast cancer can vary depending on several key factors, such as:

• The size of the tumor at diagnosis
• How effectively the cancer responds to treatment
• Whether the tumor is also hormone receptor (HR) positive or negative
• Whether the cancer has spread to the lymph nodes or other parts of the body

Survival Rates

The survival rates for HER2‑positive breast cancer differ depending on how far the cancer has spread and whether the tumor also reacts to hormones. When confined to the breast, five-year survival is very high, around 99% for HR-positive and 97% for HR-negative tumors.

Furthermore, if the cancer has spread to nearby lymph nodes, the survival rate drops to about 89% for hormone receptor‑positive cases and 84% for hormone receptor‑negative cases.

In more advanced disease, where cancer has reached distant organs, survival falls further, approximately 45% for hormone receptor‑positive and 39% for hormone receptor‑negative patients at five years.

Stage	Hormone Receptor-Positive (HR+) Five-year survival rate	Hormone Receptor-Negative (HR−) Five-year survival rate
Confined to the Breast	99%	97%
Spread to Nearby Lymph Nodes	89%	84%
Spread to Distant Organs	45%	39%

Living Well with HER2-Positive Breast Cancer

Eating well can support your overall health, help manage treatment side effects, and give your body the nutrients it needs during this journey.

What to Eat

• Fruits: Citrus fruits like oranges, lemons, and grapefruits provide antioxidants that support overall health.
• Vegetables with plant compounds: Bell peppers, celery, parsley, and lettuce contain plant compounds that may help slow tumor growth.
• Healthy fats: Seeds, walnuts, avocado, and olive oil support heart health and treatment response.
• Melatonin-rich foods: Eggs, nuts, mushrooms, and sprouted legumes.
• Plant proteins: Unprocessed soy foods like tofu, tempeh, and edamame.
• Grapes and grape seeds: Provide antioxidants that support overall well-being.

What to Avoid

• Sugary and refined foods: Limit sweets, soda, and processed snacks.
• Alcohol: It can interfere with treatment and affect hormone balance.
• Unhealthy fats: Avoid fried foods, trans fats, and heavy dairy products.
• Red and processed meats: High in saturated fat and low in beneficial nutrients.

Role of Clinical Research

Clinical research plays a vital role in advancing breast cancer treatment. By carefully studying new therapies and testing innovative approaches, researchers are continuously improving outcomes for patients.

These studies, including clinical trials for metastatic breast cancer, help identify safer, more effective treatments while expanding options for people facing aggressive forms of cancer.

Hightower Clinical is actively conducting trials to explore innovative approaches. Patients may access advanced therapies while contributing to important oncology research studies. Participating in a clinical trial can offer new options and support the fight against breast cancer. Contact us to learn more about how you can participate.

Conclusion

HER2-positive breast cancer is an aggressive but treatable form of breast cancer. Early detection, accurate diagnosis, and personalized treatment, including surgery, systemic therapy, and radiation, significantly improve outcomes.

Advances in therapy, coupled with clinical research, have transformed prognosis and survival rates, giving patients hope for longer, healthier lives. Staying informed, monitoring symptoms, and consulting healthcare professionals are key to managing this condition successfully.