Intensity-modulated radiosurgery for patients with brain metastases: A mature outcomes analysis

The purpose of this study was to evaluate the outcomes of patients with brain metastases treated by tomotherapeutic Intensity-modulated Radiosurgery (IMRS). Using retrospective chart review, we analyzed the outcomes of 78 patients (age 33-83 years, median 57 years) who underwent 111 sessions of IMRS (1 to 7 sessions per patient, median 1) for brain metastases (1 to 4 targets per IMRS session, median 1) treated between 2000 and 2005 using a serial tomotherapeutic intensity-modulated radiotherapy treatment (IMRT) planning and delivery system (Peacock, Nomos Corp., Cranberry Township, PA). Treatment planning was performed using an inverse treatment planning optimization algorithm that was optimized for IMRS. A median prescription dose of 15 Gy in combination with WBI, and median 20 Gy for IMRS alone was delivered using 2-4 couch angles over 4-24 rotational arcs. Overall survival was calculated using Kaplan-Meier analysis. To determine the effects of prognostic variables on survival, univariate and multivariate analyses using proportional hazards were performed to assess the effects of age, tumor size, the combination with whole brain irradiation, presence of multiple brain metastases, and presence of extracranial disease. The median overall survival was 6.5 months (95% CI, 5.5-7.9). One- and two-year survival rates were 24% and 10%. In multivariate analyses, age greater than 60 years was the only statistically significant variable that affected survival (hazard rate 1.29, p=0.049). We conclude that tomotherapeutic IMRS is safe and effective to treat patients with brain metastases.