Fractionated stereotactic radiation therapy for adrenal metastases: contributing to local tumor control with low toxicity.

Abstract

To report on the Erlangen (UK-Er) experience with linear accelerator stereotactic body radiation therapy (LINAC SBRT) for adrenal metastasis from various primary tumors. 33patients were treated. Primary sites included lung (n = 19), melanoma (n = 8), colorectal (n = 2), hepatocellular (n = 1), esophageal (n = 2), and breast cancer (n = 1). 14patients were treated palliatively, 19patients were treated with local curative intent. Treatment planning was done based on an exhale, mid-ventilation, and inspiration CT series. Further planning CTs were done to check for the correctness of the breathing pattern. Irradiation was performed using aNOVALIS (Varian, Palo Alto, CA, USA; Brainlab AG, München, Germany) linear accelerator. The isocenter was verified before each treatment session using the BrainLab ExacTrac® (BrainlabAG, München, Germany) system to minimize setup errors. Dose was prescribed to the planning target volume (PTV) surrounding 90% isodose. Depending on their overall performance status and prognosis, patients received clinical check-ups and radiological imaging. Median follow-up was 11months. IBM SPSS v.24 was used for univariate analysis using Kaplan-Meier curves, nonparametric Kruskal-Wallis test, and the chi-square test for frequency distributions. Toxicity was graded according to NCI CTCAE v4.0. Depending on radiologic imaging, patients were classified as stable, regression, and progression. Median survival was 11months, median PFS was 5months. Median local failure-free survival was 21months. Patients who were treated with curative intent showed abetter survival curve (p < 0.0001) and PFS (p = 0.004). BED ranged from 42 to 108.8 Gy, median BED was 67.2 Gy. Three BED groups were formed. Overall survival curves differed significantly (p = 0.046), favoring the high-dose group. 21patients were free from any adverse events or discomfort. In 7cases, agradeI toxicity was noted.