[A pilot study of TS-1 combined with cisplatin in patients with advanced gastric cancer]

TS-1 is a novel oral fluoropyrimidine anticancer agent and show synergism with CDDP. The objectives of this study were to determine the clinical toxicities, antitumor effect, survival duration, and a recommended dosage schedule in combination with TS-1 and CDDP. Patients with measurable, locally advanced or metastatic gastric cancer were candidates for the study. Three patients were assigned to one of four levels of treatment, as follows. At first, TS-1 was administered orally twice a day for 14 consecutive days followed by 14 days rest and a 24-h infusion of CDDP (70 mg/m2) was administered on day 8 of 28 every 4 weeks. Next, duration of S1 administration was increased in increments of 25% and in increments of 50%. At last, only the dose of CDDP was increased in increments of 10 mg/m2. The first three patients did not have over grade 3 hematologic and nonhematological toxicity during any course. Grade 4 neutropenia occurred during the second course in two patients consecutively in increments of 50% of TS-1. Neutropenia was considered as a dose limiting toxicity. Nonhematologic side effects generally were mild. The overall response rate including all levels was 90.9%. Three complete responses (27.3%) and 8 partial responses (63.6%) were observed among the 11 patients. At first schedule, CR was two of three patients, and PR by the other (overall response rate, 100%). Survival rate of all cases in eight months were 100%. In conclusion, a combination of TS-1 and CDDP chemotherapy showed favorable antitumor activity and less adverse reaction compared to results reported with other chemotherapy. Administration of TS-1 for 14 days followed by 14 days rest, plus CDDP (70 mg/m2) on day 8 every 4 weeks would be recommended in the view of high responsibility and low adverse reaction.