Stereotactic radiosurgery in the treatment of metastatic disease to the brain

OBJECTIVE: In recent years, stereotactic radiosurgery has been growing in p opularity as a treatment modality for metastatic disease to the brain. The technique has advantages of reduced cost and low morbidity compared with op en surgical treatment. Furthermore, it avoids the potential cognitive side effects of fractionated whole-brain radiotherapy. We undertook this study t o determine the usefulness of adjuvant radiation therapy and to determine p rognostic factors in patients treated with stereotactic radiosurgery. METHODS: We reviewed our series of patients with metastatic tumors treated using gamma knife stereotactic radiosurgery from August 1994 to February 19 99. Nonparametric methods were used to compare treatment subgroups by demog raphic features including age, Karnofsky Performance Scale score, diagnosis , and systemic disease status. Univariate and multivariate analyses of surv ival and freedom from progression were performed using Kaplan-Meier and Cox proportional hazards regression techniques. RESULTS: This study included 190 patients harboring 431 lesions who were tr eated in 263 treatment sessions. The median follow-up after radiosurgery wa s 36 weeks for all patients. The median actuarial survival from the time of radiosurgery in all patients was 34 weeks. When patients were stratified a ccording to tumor histology, those without melanoma had a median survival o f 39 weeks, and those with melanoma had a median survival of 28 weeks. The cause of death could be determined in 122 (92 %) of the patients known to h ave died during the data capture period. For patients harboring melanoma, d eath was attributable to systemic disease in 31 (47%), to central nervous s ystem-related processes in 29 (44%), and to unknown causes in 6 (9%). For n on-melanoma patients, death was attributable to systemic disease in 45 (68% ), to central nervous system-related processes in 17 (26%), and to unknown causes in 4 (6%). Significantly improved survival (P = 0.002) was observed in patients with controlled systemic disease. No significant difference in survival could be ascertained for patients presenting with up to lour lesio ns, although patients with a total tumor volume greater than 9 cc had short ened survival. No survival benefit could be demonstrated for whole-brain ra diotherapy administered either concomitantly or after radiosurgery. CONCLUSION: Factors correlated with significantly improved survival include d controlled systemic disease and non-melanoma histology. We found no signi ficant survival benefit that could be discerned from adjuvant whole-brain r adiotherapy in this patient group.