Anticipated Outcome for Metastatic Breast Cancer with Low HER2 Levels
A breast cancer diagnosis often sparks a search for answers regarding cancer progression, treatment options, and survival prospects. This is especially true for individuals diagnosed with HER2-low metastatic breast cancer, a newer designation for a category of breast cancers.
Palliative medicine specialist, Dr. Nivia Ruiz, explains the differences between HER2-low, HER2-positive, and HER2-negative breast cancers, as well as how the diagnosis of HER2-low might impact a person's life.
Understanding HER2-low Breast Cancer
HER2-low breast cancers exhibit low levels of human epidermal growth factor receptor 2 (HER2) proteins, which are responsible for breast cell growth and repair. A HER2-low diagnosis does not necessarily mean the absence of HER2 proteins or gene expression; it simply indicates insufficient amounts for the cancer to be classified as HER2-positive.
HER2-low vs. HER2-positive and HER2-negative
Healthcare providers determine HER2 status through the immunohistochemistry (IHC) test and the fluorescence in situ hybridization (FISH) test. Historically, test results led to HER2-negative or HER2-positive classifications. Now, attention focuses on HER2-low disease, which encompasses individuals with low or moderate HER2 levels. These cases may have IHC scores of 1+ or 2+, and a negative FISH test result. More than half of breast cancer cases fall under this HER2-low category. HER2-low breast cancers can benefit from targeted therapies, even in cases of triple-negative breast cancer, due to the presence of HER2 receptors.
Is HER2-low Breast Cancer Aggressive?
Like HER2-positive and HER2-negative breast cancers, HER2-low can be aggressive and potentially metastasize to other areas of the body. Studies show that HER2-low metastatic breast cancer may have higher rates of brain metastases compared to HER2-negative and HER2-positive. However, research is needed to understand how HER2-low spreads and evolves compared to other cancers.
On a positive note, a 2024 study found that approximately half of all patients diagnosed with metastatic breast cancer lived for 43.7 months (or 3.5 years). In that study, one-third of HER2-low patients with hormone receptor-negative status and less than half of those with HER2-low who were hormone receptor-positive lived within three years.
Treatment Options for HER2-low Metastatic Breast Cancer
The U.S. Food and Drug Administration has approved Enhertu® (fam-trastuzumab-deruxtecan-nxki) as a targeted treatment for HER2-low, inoperable, or metastatic breast cancer that has spread to other parts of the body. It is also approved for those who have already undergone chemotherapy for either metastatic cancer or cancer that has returned within six months of surgery. Although Enhertu may cause interstitial lung disease in up to 10 to 15% of patients, it has been shown to slow cancer growth and improve survival for people with HER2-low metastatic breast cancer.
Key Questions to Ask Your Doctor
Understanding the implications of a HER2-low metastatic breast cancer diagnosis and how it might affect one's life can be overwhelming. Some questions to ask your healthcare provider include:
- What does this diagnosis mean for me?
- What stage of disease am I in?
- What treatment options do I have?
- What are the side effects of treatment I should be aware of?
- How might my diet, nutrition, and daily activities change?
- What resources for support are available to me?
- What can I expect for my quality of life?
- How much time do I have to live, and what's my prognosis?
Adapting to Life with HER2-low Metastatic Breast Cancer
When living with HER2-low metastatic breast cancer, the primary goal of treatment is to slow down cancer growth, reduce symptoms, improve comfort, and extend life as much as possible. While metastatic breast cancer does not have a cure, making lifestyle adaptations can help individuals live well with the disease.
Support networks, such as family, friends, healthcare providers, instructors, and social workers, play a crucial role in helping navigate the cancer journey. Developing a community with others who share similar experiences can also offer emotional support.
Diet and exercise become important considerations to maintain weight and overall health during treatment. Meeting with a registered dietitian or nutritionist may be beneficial to ensure proper calorie intake and nutrient balance.
Deciding whether to continue working is a personal choice based on individual needs and capabilities. Modifications to working responsibilities, such as reduced hours, part-time work, or less physically demanding tasks, may be necessary.
An increase in medical appointments is expected, and social workers can help with transportation and emotional support. Regular monitoring of symptoms and contact with healthcare providers ensures effective treatment and disease management. Palliative care can also help with symptom management and emotional support.
Lastly, it is essential to set realistic expectations for survival and focus on making the most of each day. A positive mindset and self-care can greatly impact individual outcomes.
- The diagnosis of HER2-low breast cancer signifies the presence of low levels of HER2 proteins, which are responsible for breast cell growth and repair.
- HER2-low breast cancers can benefit from targeted therapies, as they may have HER2 receptors, even in cases of triple-negative breast cancer.
- Studies suggest that HER2-low metastatic breast cancer may have higher rates of brain metastases compared to HER2-negative and HER2-positive breast cancers.
- The U.S. Food and Drug Administration has approved Enhertu® as a targeted treatment for HER2-low, inoperable, or metastatic breast cancer, which may slow cancer growth and improve survival.
