Successful treatment of advanced gastric cancer with liver metastasis by S-1 + CDDP and S-1 therapy without surgery Abstract It is generally reported that prognosis of patients who have unresectable gastric cancer is from 3 to 5 months with best supportive care. Despite the improvement of survival after the appearance of S-1, the outcome of treatment for advanced gastric cancer is still unfavorable. Here we present a valuable case of advanced gastric cancer with synchronous liver metastasis, which was treated by S-1 + CDDP and S-1 therapy without surgery. A 58-year-old man was referred to our hospital with a diagnosis of advanced gastric cancer with liver metastasis at stage of cT3N0M1. He underwent first-line chemotherapy consisting of S-1 plus cispatin. 3 months later, a follow-up endoscopy revealed complete response (CR) of the gastric lesion. 3 months later, computed tomography (CT) also demonstrated disappearance of liver metastasis. Then he underwent maintenance chemotherapy with S-1 alone for 8 months. To date, there has been no recurrence for 6 years and 6 months since the acquisition of CR.