S-1 consists of Tegafur,Gimeracil and Oteracil Potassium. Tegafur is metabolize to Gimeracil，and slows down the metabolism of 5-FU in high DPD enzyme expression tumor cell, so that 5-FU could bring the antimetabolic fiction more efficiently. Plenty of studies support that S-1 shows a desirable effect on advanced non-squamous NSCLC, and S-1 is more convenient compare with Pemetrexed. The curative effect of Pemetrexed in the maintenance treatment of advanced non-squamous NSCLC has been proved to be valid. The purpose of our study is to explore whether S-1 could replace Pemetrexed in the maintenance treatment of advanced non-squamous NSCLC.
