S-1: A New Oral Fluoropyrimidine in the Treatment of Patients with Advanced Non–Small-Cell Lung Cancer

S-1 (also known as TS-1; Taiho Pharmaceutical Co. Ltd.; Tokyo, Japan) is a new oral fluoropyrimidine formulation that combines tegafur, 5-chloro-2,4-dihydroxypyridine (CDHP), and potassium oxonate in a molar ratio of 1:0.4:1. Single-agent S-1 has demonstrated marked activity against Non–Small-cell lung cancer (NSCLC) as well as a broad array of other solid tumors, including gastric, colorectal, breast, cervical, and pancreatic cancers. This comprehensive review summarizes the results of previous clinical studies and describes ongoing clinical trials of S-1 in advanced NSCLC. S-1 combined with platinum compounds, irinotecan, and gemcitabine has produced promising results in terms of feasibility, safety, and effectiveness. Available data have stimulated further research, including phase III trials for the first-line treatment of advanced NSCLC.