Efficacy of S-1 in Advanced Non-small Cell Lung Cancer Patients Treated ？with More Than Two Lines of Chemotherapy

Background and objective There is no standard treatment for advanced non-small cell lung cancer (NSCLC) after the failure of two lines of chemotherapy, S-1 as the third generation of fluorouracil derivate with well safety and low toxicity, presented some efficacy in lung cancer treatment. The aim of this study is to explore the efficacy of S-1 for advanced NSCLC patients treated with two or more prior chemotherapy regimens. Methods We performed a retrospective analysis of 105 NSCLC patients treated with S-1 monotherapy or S-1 contained chemotherapy as the third or more line of treatment in our hospital from January 2014 to April 2017. S-1 was administrated orally twice daily for 2 weeks, followed by one week of rest, the dose of drug was determined by body surface area (<1.25 m2, 80 mg/d; 1.25 m2-1.5 m2, 100 mg/d; ≥1.5 m2, 120 mg/d), platinum or the third-generation chemotherapy drugs could be combinedly used. Clinical response was assigned every cycle according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, Kaplan-Meier analysis was used to estimate progression-free survival (PFS). Results 42 patients received S-1 monotherapy, the other 63 patients received combined regimens, the median treatment line was 4 (3-11) and the median treatment cycle was 2 (1-14). No complete response (CR) were observed, there were 4 patients with partial response (PR), 34 patients with stable disease (SD) and 67 patients with progressive disease (PD), the objective response rate (ORR) was 3.81%, disease control rate (DCR) was 36.19%. The median PFS was 1.90 months (0.67 months-10.83 months), no difference between monotherapy and combined group (DCR: 28.56% vs 41.27%, P=0.185), the liver metastasis showed poorer PFS (1.40 months vs 1.93 months , P=0.042). Conclusion S-1 presented some activity in advanced NSCLC treated with more than two lines of treatment. The addition of other drugs cannot improve efficacy. S-1 monotherapy can be used as a choice for heavily-treated patients.？