Optimizing Detection and Management of Brain Metastases in Patients with HER-2/neu+ Breast Cancer

Abstract

Background: Brain metastases (BM) are more prevalent in patients with HER-2/neu+ breast cancer and indicate poorer prognosis. Anti-HER-2/neu agents have led to improved patient outcomes yet show decreased efficacy in BM. Best practice generally combines local and systemic interventions based on clinical discretion and ability to cross the blood brain barrier. Distinguishing radiation changes from metastatic progression complicates defining disease progression and treatment implications. Case Description: A 31-year-old female with a palpable left breast mass was diagnosed with Stage II ER-, PR-, HER-2/neu+ breast cancer. She underwent neoadjuvant chemotherapy, mastectomy with axillary node dissection, and adjuvant chest wall radiation. A year later, she was hospitalized with new seizures and found to have multiple BM which were treated with stereotactic radiosurgery (SRS). Intermittent seizures continued, and it was unclear if they were due to disease progression, radiation changes, or both. A functional MRI revealed definitive disease progression for which she ultimately underwent metastasectomy of the largest left-sided lesions. She continues with the same well-tolerated systemic therapy. Clinical Significance: Despite HER-2/neu+ breast cancer patients’ higher risk for BM, there are no current screening recommendations for CNS surveillance. Diagnosis of BM typically occurs with onset of neurological symptoms. This timing is crucial as those with BM at diagnosis have better outcomes than those diagnosed with symptomatic BM later in treatment. While SRS is a standard treatment for BM, it can cause imaging changes that mimic tumor progression leading to unnecessary interventions. Increasing serial MRI frequency and an ongoing multidisciplinary approach for patients with prior SRS may aid in differentiation between SRS-induced pseudoprogression and true disease progression, thus improving neurologic outcomes. Conclusion: Greater incidence of BM in HER-2/neu+ breast cancer calls for standardization of BM detection and management.