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

: To identify and evaluate the pretreatment and patient factors that would predict for complications after repeat radiosurgery.

: 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 cm3 (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 cm3 (range 1.10–39.20), respectively.

: 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).

: Repeat radiosurgery can be performed for recurrent tumors with minimal central nervous system toxicity, especially for benign tumors, with reasonable tumor control.