Comparison Of Different Radiotherapy Methods For Brain Metastases In Small Cell Lung Cancer Patients

Background:Brain metastases are the most common central nervous system tumors,and the most common primary site is lung cancer.However,the optimal treatment for brain metastases is still controversial.In the past,whole brain radiotherapy(WBRT)is recommended as a standard treatment for brain metastases.Some studies have shown that,stereotactic radiosurgery(SRS)resulted in less cognitive deterioration compared with WBRT.In the absence of a difference in overall survival(OS),SRS alone may be a preferred strategy for limited brain metastases,and even for brain metastases in small cell lung cancer(SCLC)patients.Since the majority of studies enrolled patients with multiple pathological types of brain metastases,and the characteristics of different pathological types transferred into the brain are distinctive.It would be unreasonable that SRS was defined as a treatment plan for various pathological types,especially for multiple brain metastases in SCLC patients.It is worth pondering whether SRS alone is suitable for brain metastases in SCLC patients.Objective:This study collected SCLC patients who treated with radiotherapy for brain metastases.By comparing the efficacy of different radiotherapy methods,this study explored the optimal radiotherapy method for brain metastases in SCLC patients.Methods:In this multi-center retrospective study,SCLC patients who had undergone WBRT or SRS for brain metastases from January 2012 to December 2018 were retrospectively screened.The primary endpoint was OS,and the secondary endpoint was intracranial progression-free survival(iPFS).The propensity score matching method was used to balance the general characteristics of patients in each group.Time to OS or iPFS was calculated by Kaplan-Meier method.And prognostic factors were performed using univariate or multivariate analyses.Results:A total of 263 SCLC patients with brain metastases were included in this study.Among of them,73 were women and 190 were men.According to accepted brain radiotherapy,the remained patients were divided into WBRT plus focal radiation boost(WBRT+boost),WBRT,and SRS groups.1.There were significant differences in OS between WBRT+boost,WBRT,and SRS groups(17.9 vs 8.7 vs 14.5 months;P=0.001).In pairwise comparisons of the OS,patients in WBRT+boost group had significantly longer OS than did WBRT(17.9 vs 8.7 months;HR,1.82;95%CI,1.30-2.55;P<0.001).However,there were no significant differences in OS between WBRT+boost and SRS groups(17.9 vs 14.5 months;HR,1.23;95%CI,0.75-2.02;P=0.432).2.Among 140 matched patients,similarly,patients who received WBRT+boost remained significantly longer OS than did WBRT(17.9 vs 11.7 months;P=0.045).Among 74 matched patients between WBRT+boost and SRS groups,however,patients who received WBRT+boost led to a longer survival than did SRS alone(21.8 vs 12.9 months;P=0.040).3.There was significant difference in iPFS between WBRT+boost,WBRT,and SRS groups(10.8 vs 6.5 vs 7.5 months;P=0.020).In pairwise comparison of the iPFS,WBRT+boost group also showed survival advantages over WBRT group(10.8 vs 6.5 months;HR,1.54;95%CI,1.12-2.12;P=0.005)and SRS groups(10.8 vs 7.5 months;HR,1.59;95%CI,1.04-2.44;P=0.032).4.Multivariate analyses showed that,female sex(HR,0.58;95%CI,0.41-0.81;P=0.002),and no or unknown extracranial metastases(HR,0.63;95%CI,0.40-0.99;HR,0.61 95%CI,0.43-0.85;P=0.011)were related to increased OS.Multivariate analysis also showed patients with more than three brain metastases(HR,1.88;95%CI,1.36-2.59;P<0.001)or those who did not receive systemic chemotherapy(HR,2.08;95%CI,1.53-2.84;P<0.001)had a poorer OS.5.Multivariate analysis showed that,female sex(HR,0.70;95%CI,0.51-0.95;P=0.021)and unknown extracranial metastases(HR,0.67;95%CI,0.48-0.92;P=0.046)were associated with increased iPFS.Patients with multiple brain metastases(HR,1.73;95%Cl,1.23-2.42;P=0.001),or those who did not receive systemic chemotherapy(HR,1.47;95%CI,1.09-1.98;P<0.001);or those who received SRS(HR,1.95;95%CI,1.25-3.05;P=0.013)were associated with poorer iPFS.Conclusions:Due to the SCLC-derived multiple brain metastases and better local control of WBRT,WBRT+boost may be a preferred strategy for brain metastases in SCLC patients.