Stereotactic Radiosurgery in Multidisciplinary Management of HER2-Positive Gastroesophageal Junction Adenocarcinoma with Large-Brain Metastases: A 9-Year Survival Case.

Patients with advanced gastroesophageal junction (GEJ) adenocarcinoma typically exhibit poor clinical outcomes, especially with brain metastases (BMs). Here, we present a notable patient with HER-2 positive advanced gastric cancer complicated with large-volume BMs who achieved long-term survival reaching 9 years through multidisciplinary treatment strategy encompassing abdominal radiotherapy, stereotactic radiosurgery (SRS), targeted therapy, and systemic chemotherapy. These findings highlight the need for balancing efficacy and safety to develop individualized radiotherapy strategies for large-volume BMs. This outcome highlights the potential benefits of comprehensive approaches and the feasibility of proactive local interventions for oligoprogressive disease. This case provides valuable experience for managing similar cases and offers new ideas for combining novel modalities like antibody-drug conjugates (ADC) drugs, immunotherapy, and radiotherapy.