Brain metastases remain a frequent and often fatal consequence of metastatic breast cancer (MBC). MBC carries a median survival of about 3 years, but that rate drops significantly when cancer cells move to the brain. A recent analysis estimates median survival in patients with brain metastases ranges from 6 months in triple-negative breast cancer (TNBC) to 21 months in human epidermal growth factor receptor 2 (HER2)–positive disease.
This news organization spoke to Kevin M. Kalinsky, MD, acting associate professor in the department of hematology and medical oncology at Emory University School of Medicine in Atlanta and director of the Glenn Family Breast Center at the Winship Cancer Institute of Emory University, about the risk for brain metastases in patients with MBC, strategies for screening and treatment, and the work being done to achieve a better understanding of the disease.
Question: Before we dig into strategies to manage MBC brain metastasis, let’s talk about the risks. When and how often do brain metastases present in patients with MBC? What factors increase the likelihood of developing brain metastasis?
Dr. Kalinsky: The biggest risk factor for MBC spreading to the central nervous system (CNS), which includes the brain and spine, is breast cancer subtype. For patients with metastatic TNBC, the risk for brain metastasis can be more than 50%. For patients with HER2-positive disease, the risk may be slightly lower, with estimates in the range of 25%-50%, whereas the likelihood of brain metastasis in patients with hormone receptor–positive MBC is significantly lower at close to 14%. In addition, patients with metastatic TNBC may have brain metastases a little earlier in their disease progression compared with patients with HER2-positive or estrogen receptor–positive breast cancers, where brain metastases generally develop a little later in the disease course.
At what point is it recommended to screen patients with MBC for brain metastasis?
Current guidelines suggest that we scan for brain metastasis in the presence of new neurologic symptoms, such as headache, dizziness, or weakness in the arms or legs. MRI, in particular, is useful for evaluating brain metastasis, especially for smaller lesions, but lesions are sometimes detected through CT imaging of the head, too.
That’s where the guidelines are now. But as our systemic agents improve, there’s always the possibility these recommendations will be revisited and potentially include imaging as screening tools in asymptomatic patients, as well.