The Clinical Application Of Stereotactic Radiosurgery For Brain Metastases From Small Cell Lung Cancer

Objective:Stereotactic radiosurgery(SRS),as an accurate method with high accuracy,high dose and real-time tracking system,has been widely used in the treatment of multiple primary intracranial tumors or brain metastases from various tissue sources,which gets unanimous approval.Patients with small-cell lung cancer have a high likelihood of developing brain metastases.However,there are few studies on stereotactic radiosurgery in the treatment of brain metastasis of small cell lung cancer,and SRS as salvage radiotherapy in most of the studies.Our study investigated the efficacy and safety of stereotactic radiosurgery in the treatment of small cell lung cancer with brain metastasis,as well as the as the efficacy of salvage SRS or initial SRS.Methods:We retrospectively reviewed the charts of 44 patients with brain metastases from small-cell lung cancer treated with CyberKnife SRS at the department of Radiation Oncology and CyberKnife Center of Tianjin Medical University Cancer Institute and Hospital from July 2006 to December 2015,and The conditions for inclusion are as follows:All patients were confirmed by pathology to be small cell lung cancer;all were small cell lung cancer patients with brain metastases rather than intracranial primary tumors;brain metastases were treated by stereotactic surgery;all patients were reviewed regularly;and the follow-up data were complete,which includes Medical records and imaging follow-up data.25 male patients and 10 female patients were include,the median age was 58 years,the median Karnofsky score was 80 scores,the median number of brain metastases was 2,the median diameter of brain metastases were 2 cm.SRS used 6 D skull based tracking with a65%-80% isodose line covering the target area,and the median dose of SRS in the treatment was 21 Gy,the median fractions was 2 times,the median BED was 30.48 Gy.Of all patients,salvage SRS after whole brain radiotherapy or prophylactic cranial irradiation failure was in 15 patients,initial SRS was in 7 patients and whole brain radiotherapy and stereotactic radiosurgery boost(defined treatment within 10 weeks)was in 13 patients.The survival of small cell lung cancer was analyzed by Kaplan-Meier method,and the factors affecting the overall survival(OS),the local control rate(LC)and distant metastases free survival(DMFS)were analyzed to evaluate the efficacy of stereotactic radiosurgery in the treatment of brain metastasis of small cell lung cancer.Results:1.In a median follow-up of 13 months,the median OS was 16 months,One-and2-year OS were 56.5%、32.8%,the median OS of salvage SRS and combined therapy were 15 months and 12 months;At the end of the follow-up period,5 patients appeared in situ recurrence,and the median recurrence time was 8 months,One-and 2-year LC were 85.3%、79.2%,respectively;the median time for intracranial distant metastases was 6 months,One-and 2-year DMFS were 51.2%、43.9%.2.During the 1.5 months from SRS,the incidence of 1-2 acute toxicity was 14%,the main clinical manifestations were headache and weak,there were no 3 grade and more acute toxicity.At the end of follow-up,the incidence of 1-2 and 3 grade toxicity was 17% and 14%,the symptoms were Nausea,vomiting and headache,which was caused by radiation-induced intracranial hypertension.3.Univariate analysis showed that no correlation factors were associated with overall survival,the local control rate and distant metastases free survival.4.Our study found that the Local contral of 6 months and 1 year in prior WBRT and no WBRT was 91.7%,73.3%,77.8%,51.9%,which means the prior WBRT may have a certain benefit on the local control rate,Although there was no significant statistical difference(P =0.095).In addition,SRS plus WBRT could bring about the same survival benefits no matter as initial treatment or salvage therapy(P=0.158).meanwhile,It was also found that the incidence of radiation brain necrosis was low when combined with planning WBRT and SRS.Which may be related to the low biological equivalent dose.Conclusion:Our study analyzed the clinical efficacy of SRS in the treatment of brain metastases from SCLC,suggesting that SRS is an effective and safe local treatment both as an initial treatment and as a salvage treatment,but there still is no substitute for the role of WBRT/PCI.In addition,planning WBRT and SRS had a lower incidence of radiation brain necrosis,which may be a new and ideal treatment mode...