A Case of Long-Term Survival after Chemotherapy for Gastric Cancer with Peritoneal Dissemination

The patient was a 58-year-old man who had undergone wide gastrectomy for gastric ulcer at 22 years of age. Endoscopic examination revealed an advanced type 3 gastric cancer in the anastomotic region. We performed total gastrectomy and D1 lymph node dissection because of the bleeding from the tumor, although peritoneal dissemination was found during the surgery. A post-operative pathological diagnosis of gastric cancer pT4b(SI, abdominal wall)N0M1(PER), pStage Ⅳ, was made. After the surgery, he was administered chemotherapy with S-1 and cisplatin. After 9 courses of the treatment, the treatment protocol was changed to an S-1 therapy regimen because of general fatigue. Four years and 8 months after the surgery, the tumor marker had increased, and CT scans revealed a dissemination nodule at the left back side of the bladder. Therefore, PTX plus Rmab therapy was administered as a second-line chemotherapy. Treatment with PTX plus Rmab resulted in tumor reduction, with an improvement of the QOL of the patient; partial response was maintained for 12 months. After 16 courses of the PTX plus Rmab treatment, tumor regrowth was detected. The treatment protocol was changed again to a nivolumab regimen. After 4 courses, the tumor marker was normalized, and CT scans revealed that the peritoneal dissemination had shrunk. Although the prognosis of gastric cancer with dissemination is very poor, it is possible to prolong survival with chemotherapy.