Efficacy and safety profile of S-1 in patients with metastatic gastric cancer in clinical practice: Results from a post-marketing survey

Background. S-1(TS-1®), a novel oral fluoropyrimidine, has been commercially available for gastric cancer in Japan. A nationwide post-marketing survey for safety was carried out after its approval. The aim of this analysis was to evaluate the efficacy and safety profile of this agent in clinical practice for patients with advanced gastric cancer registered in the postmarketing survey from our institution. Methods. Between April 1999 and April 2000, a total of 51 chemo-naive patients were registered in the survey from the National Cancer Center Hospital East. S-1 was administered at 80mg/m²/day for 4 weeks, followed by a 2-week rest, repeated every 6 weeks until disease progression, unacceptable toxicity, or the patient's refusal. Results. Of the 51 patients, 41 (80%) fulfilled the criteria of the guidelines determined by the company as appropriate patients for the drug administration. The median number of treatment courses was five. Toxicities were generally mild: grade 3 or 4 toxicities were seen in 10% or fewer patients, and no treatment-related deaths occurred. In the 47 patients with evaluable lesions, there were 2 complete responses and 18 partial responses, with a response rate of 43%. With a minimum follow-up of 2 years, median survival time and 2-year survival were 11.1 months and 33%, respectively. The majority of the 17 2-year survivors had diffuse-type histology and peritoneal metastasis and achieved an objective response. Conclusion. S-1 appears to be safe and highly active, with favorable longterm survival in patients with metastatic gastric cancer, particularly in those with diffuse-type histology and peritoneal metastasis.