A Case of Peritoneal Dissemination and Splenic Metastasis after Gastric Cancer Surgery That Could Be Controlled with Multidisciplinary Treatment.

Splenic metastasis is known to occur at the terminal stage of cancer. While peritoneal dissemination is the most frequent recurrence of gastric cancer, metastasis to the spleen from gastric cancer is very rare. Splenectomy is currently the most effective probable treatment for solitary splenic metastasis of gastric cancer; it provides a good patient prognosis. However, careful consideration of surgical indications is required, as splenic metastasis is typically accompanied by multi-organ metastasis and dissemination. One of the main cancer treatment methods is the "wait-and-see" approach using chemotherapy. In general, patients with gastric cancer are treated with systemic chemotherapy for distant metastases including peritoneal dissemination. Radiotherapy is not commonly used to prolong life in patients with gastric cancer as gastric cancer is predominantly adenocarcinoma. However, a recent report indicated that chemo-radiotherapy was performed successfully for unresectable gastric cancer, including peritoneal dissemination. Here, we present the case of a 67-year-old patient who was observed to have peritoneal dissemination and splenic metastasis after gastric cancer surgery. Once the peritoneal dissemination was localized, surgical excision and chemo-radiotherapy were performed. We treated the splenic metastasis with the "wait-and-see" strategy with chemotherapy. A complete response on imaging in accordance with the Response Evaluation Criteria in Solid Tumors was achieved using multidisciplinary treatment. Our strategy of intensive multidisciplinary therapy could be a treatment option for cases with peritoneal dissemination or splenic metastasis of gastric cancer.