PURPOSE: A triplet regimen of docetaxel, cisplatin, and S-1(DCS) is highly effective against metastatic gastric cancer. We performed this study to clarify the safety and efficacy of surgical resection in patients with initially unresectable gastric cancer, after down-staging or disease control was achieved by DCS chemotherapy.METHODS: The subjects of this retrospective study were 31 consecutive patients with initially unresectable gastric cancer, who underwent surgical resection between October, 2006 and December, 2012, after downstaging or disease control was achieved by DCS chemotherapy. We evaluated the clinicopathological factors and clinical outcomes and assessed radiographic response based on the RECIST criteria, not by central review.RESULT: Before DCS chemotherapy, 18 patients had extraregional lymph node metastasis, 5 had liver metastasis, 8 had macroscopic peritoneal metastasis, and 8 had pancreatic head invasion. Twenty-three (74.2%) of the 31 patients underwent R0 resection. Postoperative morbidity and mortality rates were 16.1 and 0%. During chemotherapy, grade 3/4 toxicities included neutropenia (54.8%), leukopenia (32.3%), and anemia (16.1%). Median progression-free survival and median overall survival (OS) were 42.1 and 56.1 months, respectively. These results were similar for all patients, except those with locally advanced disease alone. In the multivariate analysis for OS, ypN remained an independent negative prognostic factor (p = 0.018).CONCLUSION: Surgical resection after DCS chemotherapy for initially unresectable gastric cancer was safe and provided a reasonable R0 resection rate and good midterm survival.