The Prognostic Role of Tumor Volume in the Outcome of Patients with Single Brain Metastasis After Stereotactic Radiosurgery.

Abstract

Patients with single brain metastasis (SBM) have better outcomes after stereotactic radiosurgery (SRS). We analyzed our SRS database to evaluate possible prognostic factors in patients with SBM. A total of 584 patients with SBM were treated with SRS at our institution (2000-2012). Study end points were overall survival (OS), and distant and local intracranial progression-free survival (DPFS and LPFS, respectively). Multivariable analysis was performed to develop prognostic models. Median OS was 10.8 months. A total of 196 patients (36.7%) had distant progression and 102 patients (19.2%) had local progression. New SBM prognostic indices (SPIs) were devised for OS, DPFS, and LPFS. Graded prognostic assessment, neurologic symptoms (P= 0.01), and tumor volume (P= 0.02) were independently associated with OS. The SPI for OS was defined: unfavorable (OS, 7.3 months), intermediate (OS, 10.6 months), and favorable (OS, 19.8 months). For DPFS, age (P= 0.0029), tumor volume (P= 0.0002), and previous whole-brain radiotherapy (P= 0.027) were prognostic and were used to define SPI for DPFS: favorable (6-month cumulative incidence failure [CIF], 10.9%), intermediate (6-month CIF, 16.7%), and unfavorable (6-month CIF, 26.0%) (P < 0.001). For LPFS, graded prognostic assessment (P= 0.0012) and tumor volume (P= 0.0004) were significant, and defined 2 groups in the LPFS SPI: unfavorable (6-month CIF, 12.3%) and favorable (6-month CIF, 6%) (P < 0.001). This is the largest series of patients with SBM treated with SRS analyzed for OS, LPFS, and DPFS. SPI was devised for end points. Tumor volume had a significant association with all 3 end points. Neurologic symptoms, age, and previous whole-brain radiotherapy were also found to be prognostic.