Treatment Efficacy And Prognostic Factors Of Hypofractionated Radiotherapy For Brain Metastases

Background:Hypofractionated radiation therapy（HFRT）is an increasingly important treatment for brain metastases.It not only provides high-dose radiation therapy for better intracranial local control（LC）,but also minimizes adverse events.There is insufficient references on prognostic factors influencing overall survival after HFRT in patients with brain metastases.The purpose of this study was to retrospectively analyze the data of patients with brain metastases who received HFRT ± whole brain radiation therapy（WBRT）,and to investigate the therapeutic efficacy and related adverse reactions of patients with brain metastases after HFRT,and also to analyze the prognostic factors of overall survival（OS）and intracranial LC of patients.Materials and Method:This study retrospectively analyzed 79 patients who received HFRT±WBRT in the Department of Radiation Oncology,the First Affiliated Hospital of Bengbu Medical College from January 2018 to December 2020.The HFRT prescription was35–63 Gy,3–6 Gy/F;the biological effective dose was 66.3 Gy（44.8–85.1 Gy）,and28 patients underwent HFRT combined with WBRT;the WBRT prescription was30–36 Gy,2–3 Gy/F.Efficacy evaluation was performed using solid tumor efficacy evaluation criteria,radiotherapy side effects were evaluated according to RTOG radiation injury classification criteria.The Kaplan-Meier method was used to analyze event-survival curves;the log-rank method was used to test statistical differences between groups.Cox model was used to perform multivariate prognostic factors.The hazard ratios and 95% confidence intervals were reported.P < 0.05 indicated statistically significant differences.Result:At the last follow-up,62（78.5%）patients had died and 17（21.5%）patients were still alive.The median survival time was 14.3 months,the OS at 6 months and 1 year was 87.3%（69/79）and 63.3%（50/79）,respectively,and the intracranial LC at 6months and 1 year was 91.3%（63/69）and 82.0%（41/50）,respectively.Univariate analysis showed that the karnofsky performance status（KPS）,the recursive partitioning analysis（RPA）,and the state of extracranial metastases were significantly associated with OS in patients with brain metastases（KPS: P=0.023;RPA: P=0.003;the state of extracranial metastases: P=0.042）,after adjusting for confounders in multivariate analysis,KPS score,RPA score,and the state of extracranial metastases were not significantly associated with OS.Univariate analysis showed that the maximum diameter of brain metastases and the HFRT±WBRT radiotherapy mode were significantly associated with 1-year intracranial LC in patients with brain metastases（the maximum diameter of brain metastases: P=0.047;the HFRT±WBRT radiotherapy mode: P=0.026）.After adjusting for confounders in multivariate analysis,the HFRT±WBRT radiotherapy mode was significantly associated with 1-year intracranial LC（P=0.035）.The maximum diameter of brain metastases was not significantly associated with 1-year intracranial LC（P=0.060）.According to RTOG radiation injury classification criteria,8 patients（10.1%）had grade 1–2 late radiation toxicity in the central nervous system,and 6 patients（7.6%）had grade 3–4 severe radiation late toxicity.In the univariate analysis,the HFRT±WBRT radiotherapy mode was significantly associated with radiotherapy toxicity in the central nervous system.Conclusion:1.HFRT could improve intracranial LC,prolong OS in patients with brain metastases.It might be a safe,feasible and effective treatment of brain metastases.2.The KPS score,RPA score,and the state of extracranial metastases are important prognostic factors for OS in patients with brain metastases.3.The HFRT±WBRT radiotherapy mode and the maximum diameter of brain metastases were significantly associated with 1-year intracranial LC in patients with brain metastases.4.The HFRT±WBRT radiotherapy mode could improve intracranial LC in patients with brain metastases,and also increase the late toxicity of radiation in the central nervous system.