HER2-positive breast cancer is a distinct subtype characterized by elevated levels of a specific protein on the surface of cancer cells. This characteristic helps guide treatment strategies.
Understanding HER2-Positive Breast Cancer
The human epidermal growth factor receptor 2, or HER2, is a protein found on the surface of all breast cells. Normally, HER2 proteins play a role in regulating cell growth, division, and repair. In some breast cancers, however, there are too many copies of the gene responsible for making the HER2 protein, leading to an overabundance of these proteins on the cell surface.
When HER2 is overexpressed, breast cells grow and divide at an accelerated, uncontrolled rate. This makes HER2-positive breast cancer more aggressive. Approximately 15% to 20% of breast cancers are classified as HER2-positive.
Key Factors Affecting Survival
Survival outcomes for HER2-positive breast cancer are influenced by several factors. The cancer’s stage at diagnosis is a primary determinant; earlier, localized stages generally have better prognoses. This includes whether the cancer is confined to the breast, has spread to nearby lymph nodes, or metastasized to distant organs.
A patient’s overall health and age play a role in their ability to tolerate and respond to treatment. The tumor’s response to initial therapies is a significant factor; complete eradication correlates with improved long-term outcomes. The presence of hormone receptors on cancer cells can also influence treatment choices and survival.
Current Survival Rates
Survival rates for HER2-positive breast cancer are often presented as “5-year relative survival rates,” which indicate the percentage of people with the cancer who are still alive five years after diagnosis, compared to people of the same age and gender in the general population. These rates vary considerably depending on how far the cancer has spread.
For localized HER2-positive breast cancer, meaning the cancer is confined to the breast, the 5-year relative survival rate is around 99.3% for hormone receptor-positive cases and 97.3% for hormone receptor-negative cases. If the cancer has spread to regional lymph nodes or nearby structures, the 5-year relative survival rate is approximately 90.4% for hormone receptor-positive cases and 84.2% for hormone receptor-negative cases. In instances where the cancer has spread to distant parts of the body, the 5-year relative survival rate is about 45.8% for hormone receptor-positive and 39.7% for hormone receptor-negative HER2-positive breast cancer.
Impact of Targeted Therapies
Targeted therapies have transformed the prognosis for HER2-positive breast cancer. Previously, these cancers had a poorer outlook due to their aggressive nature. The introduction of drugs designed to block the HER2 protein changed treatment.
Trastuzumab, approved in 1998, was the first monoclonal antibody to directly target HER2. Its use, often with chemotherapy, improved survival rates. Subsequent therapies like pertuzumab, which inhibits HER2 dimerization, enhanced effectiveness when combined with trastuzumab and chemotherapy. These agents have reduced breast cancer recurrence and improved HER2-positive disease management.
Modern Treatment Approaches
Current treatment strategies for HER2-positive breast cancer involve a multi-modal approach, combining various therapies. This includes systemic therapies (treating the entire body) and local therapies (focusing on the tumor site).
Systemic treatments feature chemotherapy, targeted therapies that attack HER2, and immunotherapy. For metastatic HER2-positive breast cancer, a combination of trastuzumab, pertuzumab, and a taxane-based chemotherapy is a common first-line treatment. Localized treatments involve surgery to remove the tumor and radiation therapy to destroy remaining cancer cells. The specific combination of treatments is tailored to each patient, considering cancer stage and health.