Background: Multiple regimens for stereotactic radiosurgery (SRS) at the postoperative bed have shown a high local control rate and a low toxicity profile with no decrease in overall survival with the omission of whole-brain radiation therapy.
Methods: In this retrospective analysis, we evaluate our experience with postoperative SRS using a uniform regimen of 25 Gy in 5 sessions.
Results: Between April 2011 and May 2014, 75 patients were treated for 77 metastatic brain lesions with postoperative SRS in 5 sessions. The median planning target volume was 13.8 cm(3) (1.93-128.43 cm(3)) with a median follow-up for all lesions of 9.5 months (range, 1.2-38.2 months). Kaplan-Meier estimates of local control at 1 and 2 years were 88.8% and 83.9%, respectively. On univariate analysis, a trend in decreased survival with multiple brain lesions was noted (hazard ratio [HR] = 2; 95% confidence interval [CI], 0.87-4.53; P = 0.10). There was a trend towards decreased local control with radioresistant tumors (HR = 3.23; 95% CI, 0.7-22.6; P = 0.14) and planning target volume ≥17 cm(3) (HR = 3.07; 95% CI, 0.73-15.23; P = 0.12). Two (3%) patients developed radionecrosis, one of whom required craniotomy.
Conclusions: SRS with a dose of 25 Gy in 5 sessions is associated with excellent local control at the resection site with minimal toxicity in the postoperative settings in our patient population. Further investigation is required to determine if dose escalation to the postoperative cavity of radioresistant tumors improves outcomes.
Keywords: Brain metastases; Radioresistant; Stereotactic radiosurgery.
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