International collaboration of neoadjuvant stereotactic radiosurgery for brain metastases: The INTERNEO individual patient data pooled analysis

Abstract

Background and purpose: Neoadjuvant stereotactic radiosurgery (NaSRS) is an emerging treatment option for brain metastases (BrM) planned for resection. The aim of this study was to report on the efficacy and safety of NaSRS in an individual patient data pooled analysis.

Materials and methods: Patients undergoing single- and multi-fraction NaSRS for BrM at nine institutions in five countries (Australia, Canada, South Korea, Switzerland and USA) were included. Eligibility criteria included BrM from any primary malignancy and no prior local therapy. The primary endpoint was a composite of local recurrence (LR), any grade radionecrosis (RN), and/or nodular leptomeningeal disease (nLMD). Secondary endpoints included these endpoints and Grade ≥ 2 RN. Endpoints were evaluated using cumulative incidence functions.

Results: NaSRS was delivered to 179 patients with 189 BrM. Median follow-up was 28.4 months. Primary malignancies included non-small cell lung carcinoma (44 %) and melanoma (17 %). The median BrM diameter was 29 mm (IQR 21-36 mm). Single- and multi-fraction NaSRS was utilised in 100 (53 %) and 89 BrM (47 %) respectively. The median single-fraction dose was 18 Gy (IQR 16-20 Gy). Multi-fraction doses included 24 Gy in three fractions (55 %) and 27 Gy in three fractions (25 %). The 12-month incidence for the composite endpoint was 8.0 %. The 12-month incidence of LR was 4.6 %, any grade RN was 3.6 %, Grade ≥ 2 RN was 1.8 % and nLMD was 1.2 %.

Conclusion: Neoadjuvant SRS results in favourable rates of LR, RN and nLMD. We provide a global experience of this treatment approach with long-term data and the largest cohort of patients undergoing multi-fraction SRS.

Keywords: Brain metastases; Neoadjuvant; Pre-operative; Preoperative; SRS; Stereotactic radiosurgery; Stereotactic radiotherapy; Surgery.