Medical Student Department of Neurosurgery, Zucker School of Medicine at Hofstra/Northwell Bayside, New York, United States
Disclosure(s):
Sabrina Begley: No financial relationships to disclose
Introduction: Stereotactic radiosurgery (SRS) offers a focal treatment option to patients with brainstem metastases (BSM). Typically these treatments have been done using frame-based methods. We aim to review our efficacy in treating patients with BSM with specific interest in comparing results based on the utilization of mask-fixation (MF) or frame-fixation (FF).
Methods: Data were retrospectively collected for 32 patients treated with Gamma Knife SRS. Follow-up data for 49 lesions was analyzed for local control rate (LCR) and objective response rate (ORR) and compared between MF and FF groups. 16 patients were female, average age was 62 years, and median KPS at treatment was 80. The most common primary cancers were lung, breast, and melanoma and majority were pontine lesions. 18 (36%) lesions were treated with MF.
Results: Average tumor volume was 0.99 cm3 (range: 0.005 – 13.3 cm3). 39 lesions were treated with a single dose of 16 Gy (12 – 20). 10 lesions were treated in 3-5 fractions at 22.5 Gy (18 – 27). Mean follow-up was 14.2 months (1.2 to 48.2 months). 1-year LCR was 94.7%. There was no difference in ORR at last follow-up between MF vs. FF (p = 0.81), or between single vs. multiple fractions (p = 0.09). Local failure occurred in one patient with a 0.015 cc pontine colorectal cancer metastasis who was mask-immobilized for treatment with 14 Gy in a single fraction. No radiation necrosis occurred.
Conclusion : SRS for BSM achieved high LCR with no significant difference in ORR between MF vs. FF. or between single vs. fractionated SRS. Although trials have historically excluded patients with BSM, our data adds to the literature supporting SRS as a safe and efficacious treatment. This is the first study showing that MF provides equivalent, successful outcomes when compared to FF for patients with brainstem metastases.
