Multi-institutional study of 'Sandwich treatment' for motor area large brain metastases (LBM) with diameter over 3 cm.

Abstract

Background: The objective of the present study was to explore the effectiveness and safety of 'Sandwich treatment' strategy for large brain metastases (LBM) with diameter over 3 cm (minimum volume >= 15 cm³) located in motor area.

Patients and methods: Patients from four gamma knife center that received 'Sandwich treatment' were retrospectively studied from January 2016 to March 2023. The strategy was one-week treatment course including 2 stages of stereotactic radiosurgery (SRS) and using bevacizumab once during SRS gap. The tumor volume and peri-tumor edema changes were analyzed before and after 'Sandwich treatment'. Manual muscle testing (MMT) score and Barthel Index (BI) score were used to evaluate the changes of patients' movement and physical strength rehabilitation. The patients' overall survival (OS) and tumor local control (TLC) rate was calculated. Cox regression model was used to analyze the risk factors that related to TLC.

Results: 61 patients with 72 lesions received the 'Sandwich treatment'. The median prescription dose was 13.0 Gy and 12.5 Gy at the first- and second-stage SRS. The mean tumor volume at the time of 'Sandwich treatment' and 3 months later was 20.1 cm³ and 12.3, respectively (P < 0.01). The mean peri-tumor edema volume at the first- and second-stage SRS was 12.6 cm³ and 5.2 cm³, respectively (P < 0.01). Patients' median MMT score improved from 6 at the beginning to 8 at the end of 'Sandwich treatment' (P < 0.01), BI score was also greatly improved from 45 at the time of 'Sandwich treatment' to 95 after 3 months (P < 0.01). Patients' median OS was 14.0 months, and the 3, 6, 12 months OS rate was 92.0%, 86.0% and 66.0%, respectively. The TLC rate at 3, 6, 12 months was 98.4%, 93.4%, and 85.3%, respectively. Patients with lung cancer had lower risk of tumor relapse. The cumulative incidence of patient's hemorrhage and radiation necrosis was 4.92% (3/61) and 13.11% (8/61) after 'Sandwich treatment'.

Conclusions: 'Sandwich treatment' strategy is safe and effective for LBM located in motor area. The strategy could rapidly improve the patients' movement and enhance their physical strength rehabilitation.