Early Significant Tumor Volume Reduction After Radiosurgery in Brain Metastases From Renal Cell Carcinoma Results in Long-Term Survival

Purpose: To retrospectively evaluate survival of patients with brain metastasis from renal cell carcinoma (RCC) after radiosurgery. Patients and Methods: Between 1998 and 2010, 46 patients were treated with radiosurgery, and the total number of lesions was 99. The mean age was 58.9 years (range, 33–78 years). Twenty-six patients (56.5%) had a single brain metastasis. The mean tumor volume was 3.0 cm3 (range, 0.01–35.1 cm3), and the mean marginal dose prescribed was 20.8 Gy (range, 12–25 Gy) at the 50% isodose line. A patient was classified into the good-response group when the sum of the volume of the brain metastases decreased to less than 75% of the original volume at a 1-month follow-up evaluation using MRI. Results: As of December 28, 2010, 39 patients (84.8%) had died, and 7 (15.2%) survived. The overall median survival time was 10.0 ± 0.4 months (95% confidence interval, 9.1–10.8). After treatment, local tumor control was achieved in 72 (84.7%) of the 85 tumors assessed using MRI after radiosurgery. The good-response group survived significantly longer than the poor-response group (median survival times of 18.0 and 9.0 months, respectively; p = 0.025). In a multivariate analysis, classification in the good-response group was the only independent prognostic factor for longer survival (p = 0.037; hazard ratio = 0.447; 95% confidence interval, 0.209–0.953). Conclusions: Radiosurgery seems to be an effective treatment modality for patients with brain metastases from RCC. The early significant tumor volume reduction observed after radiosurgery seems to result in long-term survival in RCC patients with brain metastases. [ABSTRACT FROM AUTHOR]