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

Abstract

Purpose

To report on the Erlangen (UK-Er) experience with linear accelerator stereotactic body radiation therapy (LINAC SBRT) for adrenal metastasis from various primary tumors.

Materials and methods

33 patients 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). 14 patients were treated palliatively, 19 patients were treated with local curative intent.

Radiation treatment

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 a NOVALIS (Varian, Palo Alto, CA, USA; Brainlab AG, München, Germany) linear accelerator. The isocenter was verified before each treatment session using the BrainLab ExacTrac® (Brainlab AG, München, Germany) system to minimize setup errors. Dose was prescribed to the planning target volume (PTV) surrounding 90% isodose.

Follow-up

Depending on their overall performance status and prognosis, patients received clinical check-ups and radiological imaging. Median follow-up was 11 months.

Statistical analysis

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.

Results

Median survival was 11 months, median PFS was 5 months. Median local failure-free survival was 21 months. Patients who were treated with curative intent showed a better 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. 21 patients were free from any adverse events or discomfort. In 7 cases, a grade I toxicity was noted.

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