LINEAR ACCELERATOR-BASED STEREOTAXIC RADIOSURGERY FOR BRAIN METASTASES - THE INFLUENCE OF NUMBER OF LESIONS ON SURVIVAL

Purpose: To evaluate the influence of the number of brain metastases o n survival after stereotaxic radiosurgery and factors that affect the risk of delayed radiation necrosis after treatment. Materials and Meth ods: Between March 1989 and December 1993, 120 consecutive patients un derwent linear accelerator-based stereotaxic radiosurgery for brain me tastases identified by computed tomography (CT) or magnetic resonance image (MRI) scans, The influence of various clinical factors on outcom e was assessed using Kaplan-Meier plots of survival from the date of r adiosurgery, and univariate and multivariate analyses. Results: The me dian survival time was 32 weeks, Progressive brain metastases, both lo cal and regional, caused 25 of 104 deaths, Patients with two metastase s (n = 30) or a solitary metastasis (n = 70) had equivalent actuarial survival times (P = 0.7; median, 37 weeks; maximum, 211+ weeks), Patie nts treated to three or more metastases (n = 20) had significantly sho rter survival times (P < .002; median, 14 weeks; maximum, 63 weeks). P rognostic factors associated with prolonged survival included a pretre atment Karnofsky performance status greater than or equal to 70% and f ewer than three metastases. Delayed radiation necrosis at the treated site developed in 20 patients and correlated with prior or concurrent delivery of whole-brain irradiation and the logarithm of the tumor vol ume. Conclusion: Survival duration is equivalent for patients with one or two brain metastases and is similar to that reported for patients with a solitary metastasis managed by surgical resection and whole-bra in irradiation. Survival after radiosurgery for three or more metastas es was similar to that reported for whole-brain irradiation. (C) 1996 by American Society of Clinical Oncology.