Clinical Observational Study Of S-1Combined With Oxaliplatin (SOX) As First-line Treatment For Advanced Gastric Cancer

Objective:Gastric cancer is a worldwide malignancy, and systemic chemotherapy plays an important role in treatment. However, the standard regimen is still under debate. The efficacy and safety of S-1combined with oxaliplatin (SOX regimen) as first-line treatment for advanced gastric cancer were investigated in this clinical observational study. And the prognostic factors were explored at the same time.Methods:According to the inclusion and exclusion criteria, patients histologically confirmed of advanced gastric cancer were included. Following chemotherapy regimen was applied to all the patients:oral administration of S-140-60mg/m twice daily on days1-14, and oxaliplatin100mg/m2administered as a2-hour intravenous infusion on day1. Treatment courses were repeated every21days, and at least2cycles were given. Eficacy was evaluated according to the RECIST1.1standard. Adverse events after treatment were evaluated according to the CTCAE-V3.0. The primary endpoint were progression-free survival (PFS) and overall survival time (OS), and the survival curves were depicted by Kaplan-Meier method. The secondary endpoints were response rate (RR), disease control rate (DCR) and adverse effect. Simultaneously, we analyzed the possible factors that could affect the survival time, including age, gender, chemotherapy cycles, short-term effect after chemotherapy, palliative surgery, performance status (ECOG score), pathological type, metastatic sites, the hemoglobin and transaminase levels before chemotherapy, and the level of tumor marker (CA-125, CEA) before chemotherapy. Cox-regression analysis was used to establish the prognostic factors for futher validation.Results:25patients were enrolled in this study.4were in stage Ⅲc, and21were in stage Ⅳ at baseline evaluation. The ratio of males to females was14to11. The mean patient age was57.4±11.9years (28-75years). All patients had a performance status (ECOG) of0-2. The mean number of chemotherapy cycle was5.1±1.3(2-7). All25patients were evaluable for efficacy. After last administration,2patients (8%) achieved a complete response, and8patients (32%) partial response.9patients (36%) evidenced a stable disease, and6patients (24%) progressed during the course of the treatment. The response rate was40%, and disease control rate was76%. No patient was lost during the follow-up prior to evaluation. At the end of study, there were still76%(19/25) patients in disease control state. The median of progression-free survival time was9.8months (95%CI7.3-12.3months), and the median of the survival time was10.6months (95%CI8.4-12.9months). Single factor analysis shows that ECOG score was the prognostic factors of survival time. Meanwhile, there’s no statistic significant correlation with age, gender, number of chemotherapy cycles, short-term effect after chemotherapy, palliative surgery, pathological type, metastatic sites, hemoglobin and transaminase levels before chemotherapy, or the level of tumor marker before chemotherapy. Cox-regression analysis also shows that, ECOG score was the independent prognostic factor of survival time. The main adverse events included myelosuppression, gastrointestinal reactions and peripheral nerve toxicity, mainly in grade1-2. The adverse events of grade3-4were leukopenia (4%), anemia (24%), thrombocytopenia (24%) and peripheral nerve toxicity (4%). No one case of treatment-related death was observed.Conclusion:S-1combined with oxaliplatin was effective and tolerable as first-line treatment for advanced gastric cancer. Patients with better performance status might have a more pronounced survival benefit. SOX regimen was one of the good choice for the first-line treatment of advanced gastric cancer, and the large-scale randomized controlled clinical trials were needed for further verified.