A Case Report of Gastric Cancer Excised after Neoadjuvant Chemotherapy and Long-Term Survival Achieved after NivolumabAdministration for Peritoneal Dissemination

The patient was a 64-year-old man with Type 3 advanced cancer in the upper body of the stomach. The preoperative tumor marker value of CA19-9 was abnormally high, but there was no proof of distant metastasis or peritoneal dissemination. The first operation was an exploratory laparotomy due to direct tumor invasion to the pancreas. Systemic chemotherapy was performed for tumor reduction. First, S-1 plus cisplatin therapy was administered for 4 courses but discontinued because of renal dysfunction and thrombocytopenia. In the second-line therapy, ramucirumabplus paclitaxel therapy was administered for 7 courses. Since the tumor invasion to the pancreas turned to be clear based on a CT scan, total gastrectomy with regional lymphadenectomy was performed. However, 5 months after surgery, a single nodule appeared in the upper abdomen that was suspected to be peritoneal dissemination. Nivolumab therapy was administered for 16 months without tumor enlargement or any adverse effect. Recently, there has been a marked development in chemotherapy for gastric cancer. Unresectable cases became operable after the administration of appropriate chemotherapy. In our case, nivolumab therapy had no adverse effect. However, serious adverse effects have been reported by several authors which suggests that regular examinations for interstitial pneumonia, hypothyroidism, and other adverse effects are important.