Local Control And Adverse Reactions Of Stereotactic Radiotherapy For Brain Metastases

Background and Purpose:Brain metastases are one of the most common intracranial malignancies in adults,with an incidence of 20%-40%.With the development of medical imaging technolo Gy and the prolongation of survival time of tumor patients,the incidence of cancer is gradually increasing.Local treatments for BMS include surgery and radiotherapy,including whole-brain radiotherapy（WBRT）and stereotactic radiotherapy（SRT）.In recent years,SRT has been widely used in the radiotherapy of brain metastases due to its advantages of small field cluster,large variation of dose gradient around target area and concentration of dose distribution.The purpose of this study was to investigate the efficacy and adverse reactions of stereotactic radiotherapy for patients with brain metastases,and to provide reference for the clinical treatment of brain metastases.Material and Method（s）:A total of 75 patients with brain metastases who received stereotaxic radiotherapy in the department of Radiotherapy from July 2017 to July 2020 were retrospectively analyzed,including 41 patients with single brain lesions and 34 patients with multiple brain lesions（2-12）,with a total number of 151 lesions.Clear pathological diagnosis was obtained by surgery or puncture,and intracranial lesions were confirmed by craniocerebral enhanced MRI.A total of 50 patients were treated with FSRT,with a median dose of 35Gy;A total of 25 patients were treated with SRS,with a median dose of 20 Gy.The RECIST evaluation standard of WHO solid tumor efficacy was used for efficacy evaluation.Group T test was used to compare measurement data,and Chi-square test or Fisher’s exact probability test was used to compare counting data.The univariate and multivariate analyses of overall survival（OS）and local control rate（LCR）were evaluated by Cox proportional risk model.p <0.05 was considered statistically significant.Results:The median follow-up time of all patients was 8.7 months（2.1-38.6 months）,and the median survival was 9.3 months.According to THE WHO RECIST evaluation criteria for solid tumor efficacy,complete response（CR）accounted for 18.7%（14/75）.Partial response（PR）was 61.3%（46/75）,and objective response rate（ORR）was 80%（60/75）.The incidence of central nervous system adverse reactions was 16%.Univariate analysis showed that 1-year local control rate of patients treated with stereotactic radiotherapy combined with WBRT was better than that of patients treated with stereotactic radiotherapy alone（p=0.031）.The target bioequivalent dose was correlated with local control of tumor,and the local control rate was higher in PATIENTS with BMS with BED≥50.4Gy（p=0.020）.Univariate analysis of radiotherapy adverse reactions showed that WBRT combined with WBRT was significantly associated with the occurrence of acute radiotherapy adverse reactions（p=0.030）.Kaplan-meier analysis showed that KPS score and extracranial tumor control and lesion size were significantly correlated with 1-year OS in patients with BMS.（p=0.042,p =0.007,p=0.023）Conclusion:1.Stereotactic radiotherapy is one of the effective treatment methods for local treatment of brain metastases,which can achieve higher tumor control rate and longer survival time.2.Target bioequivalent dose and whether combined with WBRT therapy are important factors affecting LC in patients with BMS;The maximum size of BMS,KPS score before treatment,and status of extracranial tumor were significantly correlated with OS,which could be used as the basis for the selection of clinical treatment for BMS patients.Stereotactic radiotherapy combined with WBRT increased PATIENTS ’LCR with no significant overall survival benefit,but also increased acute central nervous system radiotherapy side effects.3.There were no significant differences in LC,OS and radiotherapy side effects between FSRT treatment and SRS treatment,but FSRT could treat more and larger BMS.