Histological complete response in a case of advanced gastric cancer treated by chemotherapy with S-1 plus low-dose cisplatin and radiation

A 76-year-old male was diagnosed with stage IV (cT4, cN2, cP0, cH0, cM0) gastric carcinoma with a type 3 tumor in the cardia with lymph node metastases, determined by gastrofiberscope and abdominal computed tomography (CT). The patient was treated with chemotherapy consisting of S-1 and low-dose cisplatin (CDDP) during the first cycle (3 weeks). S-1 was orally administered at a dose of 100 mg/day (60 mg/m²/ day) on days 1-21. CDDP was infused at a dose of 10 mg/day (6 mg/ m²/day) on days 1-5, 8-12 and 15-19. After this cycle, the clinical response was evaluated as no change (NC). In the second cycle, radiation therapy (2 Gy/day for 5 days/week) was initiated along with the chemotherapy. The CDDP dose was decreased to 7.5 mg/day because of the grade 3 thrombocytopenia and grade 2 leukocytopenia that occurred during the first cycle. The second cycle was stopped at a total radiation dose of 48 Gy due to grade 3 thrombocytopenia and grade 2 leukocytopenia. Examination after this treatment showed remarkable reduction of tumor volume in the primary lesion and lymph nodes, which was defined as a partial response (PR). The patient then underwent total gastrectomy with D1 lymph node dissection. The postoperative course was uneventful without surgical complications. At this time, no gastric cancer cells were detected in the resected specimen, including the primary lesion and lymph nodes, confirming a pathological complete response (CR grade 3). Thus, the chemo-radiation treatment regimen described here may be a potent tool to control advanced gastric carcinoma.