Analysis of repeat stereotactic radiosurgery for progressive primary and metastatic CNS tumors

Purpose: To identify and evaluate the pretreatment and patient factors that would predict for complications after repeat radiosurgery. Methods and Materials: The data from 26 patients who underwent reirradiation with Gamma Knife surgery after a previous procedure in the same or subjacent location were available for evaluation. The range of follow-up was 1-45 months (mean 10). The mean minimal and maximal initial dose and volume for all 26 patients was 16.2 Gy (range 12-22), 31.0 Gy (range 22.2-40.0), and 12.4 cm(3) (range 1.20-70.84), respectively. The mean marginal and maximal repeated radiosurgery dose and volume for all 26 patients was 14.9 Gy (range 12-22.5), 29.7 Gy (range 18.0-45.0) and 12.8 cm(3) (range 1.10-39.20), respectively. Results: Tumor control was significantly better statistically (p = 0.0129) for benign tumors (6 of 6, 100% actuarial rate at 4 years) compared with malignant tumors (7 of 20, 35% actuarial rate at 3 years, 3 of 4 metastatic tumors and 2 of 10 primary malignant gliomas). The retreatment volume for radiosurgery correlated significantly with the probability of neurologic decline (any cause) (P = 0.0181). Conclusion: Repeat radiosurgery can be performed for recurrent tumors with minimal central nervous system toxicity, especially for benign tumors, with reasonable tumor control. (C) 2002 Elsevier Science Inc.