Dose-Reduced Stereotactic Radiosurgery for Brain Metastases in the Era of CNS-Penetrating Systemic Therapies

• DOI: 10.1016/j.ijrobp.2018.07.823
• Publication Date: 2018-10-19T21:31:32Z
• Authors: A.J. Huang; K.E. Huang; R.J. Kumar; A. Goel; N. Harandi; M.C. Rounsaville; R.E. Abendroth; J.W. Lee
• Keywords: Stereotactic radiation therapy; Systemic therapy

In the era of CNS-penetrating systemic therapies such as checkpoint inhibitors and small molecule inhibitors, higher intracranial control rates well radionecrosis have been reported due to radiosensitization effects these therapies. We wished determine if dose-reduced SRS could achieve adequate while minimizing risk symptomatic radionecrosis. Our institution implemented a regimen, typically 18Gy in 1fx for 1-3 lesions all <1 cm, 2fx >3 simultaneously treated lesions, with <2 cm. For larger or resection cavities we would prescribe dose 21Gy 3fx 24Gy 4fx. Median GTV-PTV expansion was 2mm (range 0-5mm). reviewed patients who received brain metastases between 2014-2015 documented lesion location, prior radiation, volume, largest single dimension, occurred. Cancer subtype, therapies, cause death, performance status included well. Cox proportional hazards models were used factors affecting local control. From 2014-2015, 242 from 59 using SRS. Minimum follow-up 2-years. The majority came melanoma primary (n=140) remainder lung (n=61), breast (n=13), gastrointestinal ovary (n=7), bladder (n=2), unknown (n=1) primary. Eighteen resected before (85%) therapy concurrently subsequently after Local 64% at 1-year, 61% Radionecrosis occurred 7 (2.9%). (n=172) <1cc, 52 1-10cc volume. remaining 18 10-98cc On multivariate analysis, maximum dimension (p=0.018), surgical (p=0.03) independent predictors failure. Overall survival 48% 1-year 36% Neurological death seen 25% (n=15) patients. modern has acceptable very low