Focal Management of Large Brain Metastases and Risk of Leptomeningeal Disease.

Purpose: Surgery is often used for large or symptomatic brain metastases but is associated with risk of developing leptomeningeal dissemination. Emerging data suggest that fractionated stereotactic radiation therapy (FSRT) is an effective management strategy in large brain metastases. We sought to retrospectively compare leptomeningeal disease (LMD) and local control (LC) rates for patients treated with surgical resection followed by radiosurgery (S + SRS) versus FSRT alone.

Methods And Materials: We identified all patients with a brain metastasis ≥3 cm in diameter treated from 2004 to 2017 with S + SRS or FSRT alone (25 or 30 Gy in 5 fractions) who had follow-up imaging. LMD was defined as focal or diffuse leptomeningeal enhancement that was >5 mm from the index metastasis. Categorical baseline characteristics were compared with the χ test. LMD and LC rates were evaluated by the Kaplan-Meier (KM) method, with the log-rank test used to compare subgroups.

Results: A total of 125 patients were identified, including 82 and 43 in the S + SRS and FSRT alone groups, respectively. Median pretreatment Graded Prognostic Assessment in the S + SRS and FSRT groups was 2.5 and 1.5, respectively ( < .001). Median follow-up was 7 months. The KM estimate of 12-month LMD rate in the S + SRS and FSRT groups was 45% and 19%, respectively ( = .048). The KM estimate of 12-month local control in the S + SRS and FSRT groups was 70% and 69%, respectively ( = .753). The 12-month KM estimate of grade ≥3 toxicity was 1.4% in S + SRS group versus 6.3% in the FSRT alone group ( = .248). After adjusting for graded prognostic assessment (GPA), no overall survival difference was observed between groups ( = .257).

Conclusions: Surgery is appropriate for certain brain metastases, but S + SRS may increase LMD risk compared with FSRT alone. Because S + SRS and FSRT seem to have similar LC, FSRT may be a viable alternative to S + SRS in select patients with large brain metastases.