A pooled analysis of arc-based image-guided simultaneous integrated boost radiation therapy for oligometastatic brain metastases.

PURPOSE: To report pooled overall survival and time to radiological intracranial progression results related to arc-based image-guided radiotherapy for dose-escalation of oligometastatic disease of the brain. METHODS AND MATERIALS: Anonymized patient, tumor, and treatment data were pooled from the VU University medical center (VUmc) and the London Regional Cancer Program (LRCP) for patients treated with whole brain radiotherapy (20 Gy/5 VUmc, 30 Gy/10 LRCP) with simultaneous integrated boost (SIB) to individual intracranial lesions (40 Gy/5 VUmc, 35-60 Gy/10 LRCP) to perform survival/intracranial control outcome analyses. RESULTS: A total of 120 patients were treated by both the LRCP (n=70) and VUmc (n=50) between 2005 and 2010. Median lesional dose BED3,10 for the entire cohort of patients were 147 and 72 Gy, respectively. Median follow-up for the entire cohort of patients was 4.7 months with median follow-up of 5.2 months for living patients. On multivariable analysis, primary lung cancer (HR 2.044), presence of systemic metastatic disease (HR 1.937), and lower baseline WHO performance status (HR 1.742) were significant (p<0.05) predictors of shorter overall survival. Cumulative brain metastases volume (HR 1.014, p=0.06) was of borderline significance on analysis of intracranial control. CONCLUSIONS: This pooled analysis has provided robust outcome data regarding the use of arc-based radiotherapy with SIB.