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

Abstract

To retrospectively evaluate survival of patients with brain metastasis from renal cell carcinoma (RCC) after radiosurgery. 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 cm(3) (range, 0.01-35.1 cm(3)), 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. 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). 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.