P11.57.B Combined surgery and radiotherapy for brain metastases. Retrospective analysis of a consecutive cohort of 118 patients

Abstract

Background Despite current advances in systemic therapy for brain metastases, neurosurgery remains the preferred method of choice in patients with limited brain metastases. Postoperative radiotherapy indicated to reduce the risk of local recurrence is recommended in all patients after surgery. The aim of this retrospective study is to describe clinical characteristics and survival outcomes in consecutive cohorts of patients treated by this combined local treatment. Material and Methods Clinical data were retrieved from electronic medical records for consecutive patients who underwent surgery for brain metastases between 2007 and 2019. All patients underwent postsurgery radiotherapy. Local progression free survival (localPFS) evaluated the local control at the operated site. DistalPFS at the other parts of the brain. Univariable and multivariable analysis of survival characteristics was performed. The Median follow-up was 49 months. Results A total of 118 patients were included (54% women, median age 60 years, median Karnofsky index 80% at the time of radiotherapy). Single metastasis was treated in 66%, while 11% presented with more than 3 metastases. The most common primary diagnosis was lung cancer (33%) and breast (20%). Radical surgery was achieved in 92/117 (79 % of patients). In total, only 48/118 (41%) of patients underwent targeted radiotherapy (mostly fractionated stereotactic radiotherapy of 25Gy in 5 fractions). Significantly more patients (p<0.001) underwent targeted radiotherapy during 2016-2019 (45/48) compared to 2007-2015 period (3/48). A total of 20% of those who underwent postsurgery whole brain radiotherapy (WBRT) had a special technic of hippocampal sparing WBRT of WBRT with simultaneous integrated boost to remaining brain metastases. Median overall survival (OS) for all patients was 9 months (6.2 - 12), median localPFS 22 months (14 - not reached), median distalPFS 11 months (6.8 - 27) and median extracranialPFS 11 months (5.9 - 15). A significant (p=0.00017) difference in OS was while grouping patients according to Graded prognostic assessment (brainmetgpa.com). Significantly better OS was in the cohort of patients with targeted stereotactic radiotherapy (17months) vs. WBRT (5.6 months; p=0.00069) with no difference in local PFS, distal PFS or extracranialPFS. Multivariable analysis revealed type or radiotherapy, control of primary tumor, number of brain metastases 1-2 and the possibility to discontinue corticosteroids to be independent variables for OS. Conclusion Targeted fractionated stereotactic radiotherapy to tumor bed after metastasectomy was associated with improved survival compared to postsurgery WBRT in our cohort. Stereotactic radiotherapy should be preferred in all workplaces with adequate radiotherapy technology. Supported by Ministry of Health of the Czech Republic AZV, NV18-03-00469 and NV18-03-00398.