Hypofractionated Radiotherapy for 35 Patients with Adrenal Metastases: A Single-Institution Experience

Objective: To investigate the clinical outcomes of hypofractionated radiotherapy for adrenal metastases. Materials and Methods: We retrospectively reviewed patients diagnosed with adrenal metastases and treated with hypofractionated radiotherapy, who did not receive adrenalectomy or have disease progression after chemotherapy, from 2007 to 2019. The Kaplan-Meier method was used to estimate local control rate (LCR), progression-free survival (PFS), and overall survival (OS). Univariate analysis was performed using Log rank test. Results: Thirty-five patients with 42 lesions were enrolled, and the lung was the most common primary site (80.0%). The median follow-up time was 46.4 months. The median volume of GTV and PTV was 23.2 cm(3) (range: 3.5-97.8 cm(3)) and 38.3 cm(3) (range: 10.2-135.6 cm(3)), respectively. The main dose regimens were 60 Gy delivered in 4-15 fractions, with the median dose of PTV being 60 Gy (range: 40-66.3 Gy) and the biologically effective dose (BED) being 84 Gy (range: 56-110 Gy). The 1-year and 2-year LCR, OS, and PFS were 92.7% and 88.1%, 76.9% and 45.4%, and 25.1% and 14.4%, respectively. Univariate analysis showed that chemotherapy, disease-free interval from primary disease diagnosis to adrenal metastases diagnosis, and age were significant factors for LCR, OS, and PFS, respectively (p=0.017, 0.049, and 0.004, respectively). No more than grade III toxicities were observed. Conclusion: As a non-invasive approach, hypofractionated radiotherapy is safe and effective for metastatic adrenal lesions, without serious complications.