A long-term survival case of unresectable gastric cancer with multidisciplinary therapy including immunotherapy and abscopal effect.

The prognosis of unresectable gastric cancer remains poor. Multidisciplinary treatment of unresectable gastric cancer is, therefore, thought to be essential for improving patients' outcomes. Here, we report a successful case of multidisciplinary therapy for unresectable gastric cancer. The patient was a 69-year-old woman who was diagnosed with type 2 gastric cancer with remote lymph node metastases and peritoneal dissemination. Although shrinkage of the primary lesion and remote lymph nodes were observed following chemotherapy, we performed distal gastrectomy to deal with continuous bleeding from the primary lesion. Combination therapy with radiation and chemotherapy was effective for multiple metastases in both subclavian lymph nodes and metachronous multiple axillary lymph nodes. Nivolumab combined with radiation therapy also induced regression of remote lymph node metastases, peritoneal dissemination, and adrenal metastasis. Abscopal effects, i.e., shrinkage of the non-irradiated lesions, were also observed. Thus far, the patient has been able to maintain a good quality of life while receiving continued nivolumab therapy. Multidisciplinary therapy including immunotherapy and abscopal effect may improve the quality of life and contribute to long-term survival of patients with unresectable gastric cancer.