Breast Cancer Explained: Understanding Types, Recognizing Symptoms, and Advanced Treatment Approaches
Learn about breast cancer types, symptoms, diagnosis, and treatments for breast cancer at Vejthani Hospital’s Breast Center.
Approximately one in five breast cancers are classified as HER2-positive. This means the cancer cells have extra copies of the gene that produces the Human Epidermal Growth Factor Receptor 2 (HER2) protein, making these tumors generally more aggressive than other types of breast cancer.
Over the past two decades, new medicine has revolutionized the treatment for HER2-positive. The first HER2-targeted therapy, trastuzumab (Herceptin) combined with chemotherapy, was a major breakthrough. This treatment boosted overall survival rates by 30% and cut the risk of the cancer returning by 50%.
Understanding HER2-Targeted Therapies
Conventional treatments like surgery, radiation, and chemotherapy remain essential, but they are frequently used in combination with newer therapies that specifically target the HER2 protein in various ways. These targeted treatments fall into three main categories:
1. Monoclonal Antibodies
These are the most common targeted therapies. They are administered via intravenous infusion or subcutaneous injection and function by mimicking the body’s natural immune system antibodies. They physically attach to the HER2 receptors on the cancer cells, which blocks the growth signals the cells would normally receive. They also signal the immune system to attack and destroy the cancer cells, preventing them from multiplying and killing the cancer cells.
Examples:
- Trastuzumab (Herceptin): Used for both early-stage and advanced disease.
- Pertuzumab (Perjeta): Often paired with trastuzumab and chemotherapy for early-stage or advanced cancer.
- Trastuzumab/pertuzumab (Phesgo): A combination of trastuzumab and pertuzumab in one single subcutaneous injection for more convenience.
- Margetuximab (Margenza): Typically combined with chemotherapy for advanced cancer.
2. Tyrosine Kinase Inhibitors (TKIs)
Kinases are proteins that instruct cells to grow. TKIs are small molecules that block this protein, effectively stopping the signal and inhibiting cancer growth.
- Lapatinib (Tykerb): Oral medication for people with advanced breast cancer.
- Neratinib (Nerlynx): Oral medication for early-stage breast cancer and metastatic cancer that has not responded to other HER2-targeted drugs.
- Tucatinib (Tukysa): Oral medication for advanced breast cancer. It is typically used in combination with trastuzumab and chemotherapy after at least one prior targeted medicine has been tried.
3. Antibody-Drug Conjugates (ADCs)
These innovative drugs link a monoclonal antibody directly to a potent chemotherapy agent. The antibody component attaches to the HER2 protein on the cancer cell, acting as a guide that delivers the chemotherapy directly inside the cell and destroys it.
- Ado-trastuzumab emtansine (Kadcyla): Used for certain early-stage and advanced breast cancers.
- Trastuzumab deruxtecan (Enhertu), or T-DXd: Used for advanced breast cancers. This medicine is also prescribed for some “HER2-low” breast cancers, which have a lower HER2 protein level than standard HER2-positive cancers.
Managing Side Effects of HER2-targeted therapies
Most HER2-targeted therapies, especially for early-stage disease, are given alongside chemotherapy to maximize effectiveness. This means patients may experience typical chemotherapy side effects, in addition to the side effects of HER2-targeted therapy.
- Monoclonal Antibodies: Carry an elevated but rare risk of heart issues (cardiac toxicity), which is often reversible. Your doctor will likely perform regular heart monitoring (like an echocardiogram) during treatment.
- Tyrosine Kinase Inhibitors: Commonly cause side effects such as diarrhea and rashes.
- Antibody-Drug Conjugates: Increase the risk of lung disease. Your doctor will monitor patients for symptoms like a cough, shortness of breath, or fever.
Many people may experience only mild or minimal side effects. Your doctor can manage these symptoms by decreasing the dosage, postponing the next cycle, or changing to an alternative therapy.
Determining the Right Therapy
The doctor will select a targeted therapy based on several factors, including the stage of the disease, prior treatments the patient has received, and the patient’s overall health.
- Early breast cancer
When the tumor is small and localized to the breast, treatment usually involves surgery, followed by chemotherapy and one or more monoclonal antibodies. A maintenance dose of the targeted therapy typically continues for a total of 1 year. Radiation or hormone-blocking therapies can be added when indicated.
- Locally advanced breast cancer
When the tumor is larger and has spread to the underarms, the initial step may be chemotherapy and one or two monoclonal antibodies to shrink the tumor and evaluate its response. This is then followed by surgery, the targeted maintenance dose for about a year, and possibly additional treatments like radiation or hormone-blocking therapies.
- Advanced or metastatic breast cancer
HER2-targeted therapies are usually recommended in the advanced stage when the cancer cells have metastasized, sometimes on their own or with chemotherapy or hormone-blocking therapies. The specific regimen is switched as needed, based on follow-up scans showing how the cancer responds. Surgery and radiation are generally not recommended in this scenario. A common initial treatment might be chemotherapy with two monoclonal antibodies, which could later be adjusted to a regimen that includes an antibody-drug conjugate, a kinase inhibitor, chemotherapy, and a monoclonal antibody used as monotherapy or combination treatment.
For more information, please contact
Breast Center, Vejthani International Hospital
Call: (+66)2-734-0000 Ext. 2715, 2716
English Hotline: (+66)85-223-8888
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