Efficacy Analysis Of First-line Immunotherapy In Combination With Chemotherapy Versus Chemotherapy Alone In Extensive-stage Small-cell Lung Cancer: A Single-center Study

Objective: The purpose of this study was to compare the real-world efficacy difference between first-line immunotherapy combined with chemotherapy and chemotherapy alone in extensive stage small cell lung cancer(ES-SCLC),and to evaluate the clinicopathological factors and inflammatory indicators that may be related to long-term benefits in order to guide the prognosis and survival of patients.Methods: Pathologically confirmed ES-SCLC patients admitted to the Cancer Center of Shengjing Hospital Affiliated to China Medical University from January 2018 to November 2022 who had received first-line immunotherapy combined with chemotherapy or standard chemotherapy(EP/EC)were retrospectively collected.General clinicopathological features,treatment regimens,treatment effect,immunoinflammatory indicators before and after treatment were recorded.Kaplan-Meier method was used to estimate the time of progression-free survival(PFS)and overall survival(OS)of the whole patients and subgroups,and log-rank test was used to compare the differences between groups,and survival curves were drawn.Prognostic factors related to PFS and OS were analyzed by univariate analysis and COX multivariate regression.The optimal critical value was determined by constructing receiver operating characteristic curve(ROC)curve for continuous variables with the maximum Youden index tangent point.The long-term survival benefit of first-line therapy was defined as greater than the upper quarter of PFS.Single-factor and multi-factor logistics regression were used to analyze the correlation between different factors and long-term survival benefits.P<0.05 indicated statistically significant difference.Results: A total of 79 patients with ES-SCLC were included in the first-line treatment,including 27 patients(34.2%)who received first-line immunization combined with EP/EC chemotherapy and 52 patients(65.8%)who received first-line EP/EC chemotherapy alone.The median PFS of the immunotherapy combined with chemotherapy group and chemotherapy alone group were 6.77 vs 5.91 months(HR:0.490;95%CI: 0.275-0.983;P=0.044),the median OS was 11.07 vs 14.36 months(HR:0.590;P=0.131).Univariate analysis and multivariate analysis of the population showed that first-line immunotherapy combined with chemotherapy(P=0.044)was associated with better PFS.Liver metastasis and pre-treatment lymphocyte count > 0.95 were associated with poor OS.The proportion of patients with long survival benefit(>10.56months)after first-line treatment was 7 cases(25.9%)in the immunotherapy group and15 cases(28.8%)in the chemotherapy alone group.Univariate analysis and multivariate analysis of the population showed that first-line immunotherapy combined with chemotherapy(P=0.044)was associated with better PFS.Liver metastasis and pre-treatment lymphocyte count > 0.95 were associated with poor OS.The first response(CR/PR)was significantly different between the two groups(P < 0.05).Univariate analysis and further multivariate analysis of the population benefiting from long-term survival showed that in the overall population of ES-SCLC,the number of distant organ metastases was less than 2,which may benefit from long-term survival efficacy.Conclusions: Single-center real-world data showed that immunotherapy combined with EC/EP chemotherapy significantly prolonged PFS but failed to improve OS in first-line treatment of ES-SCLC compared with chemotherapy alone.Liver metastasis status and pre-treatment lymphocyte count are independent predictors of OS for first-line treatment of ES-SCLC.Patients with PR/CR as the first assessment of efficacy were associated with a long-term survival benefit.