Abstract Background Brain metastases from gastric cancer are difficult to treat and their prognosis is poor. Despite various possible treatments, the survival rate of such patients is still unsatisfactory; therefore, new treatment modalities or combinations of therapies need to be explored. Case presentation We herein discuss a case of a 38-year-old man initially diagnosed with a gastric cancer brain metastasis. At first, only stereotactic radiosurgery (SRS) was performed, but it was not effective. After the brain and systemic metastases progressed, SRS and anti-PD-1 therapy were administered in combination, and the brain and intra-abdominal metastatic lesions responded satisfactorily. Conclusion The combination of anti-PD-1 therapy and SRS could be effective against gastric cancer with brain metastases.
