Outcomes and toxicities in oligometastatic patients treated with stereotactic body radiotherapy for adrenal gland metastases: A multi-institutional retrospective study

A Baydoun,H Chen,I Poon,S Badellino,R Dagan,D Erler,M.C Foote,A.V Louie,K.J Redmond,U Ricardi,A Sahgal,T Biswas

doi:10.1016/j.ctro.2021.09.002

Abstract

BackgroundStudies reporting SBRT outcomes in oligometastatic patients with adrenal gland metastases (AGM) are limited. Herein, we present a multi-institutional analysis of oligometastatic patients treated with SBRT for AGM. Material/methodsThe Consortium for Oligometastases Research (CORE) is among the largest retrospective series of patients with oligometastases. Among CORE patients, those treated with SBRT for AGM were included. Clinical and dosimetric data were collected. Adrenal metastatic burden (AMB) was defined as the sum of all adrenal GTV if more than one oligometastases is present.Competing risk analysis was used to estimate actuarial cumulative local recurrence (LR) and widespread progression (WP). Kaplan-Meier method was used to report overall survival (OS), local recurrence-free survival (LRFS), and progression-free survival (PFS). Treatment related toxicities were also reported. ResultsThe analysis included 47 patients with 57 adrenal lesions. Median follow-up was 18.2 months. Median LRFS, PFS, and OS were 15.3, 5.3, and 19.1 months, respectively. A minimum PTV dose BED10 > 46 Gy was associated with an improved OS and LRFS. A prescribed BED10 > 70 Gy was an independent predictor of a lower LR probability. AMB>10 cc was an independent predictor of a lower risk for WP. Only one patient developed an acute Grade 3 toxicity consisting of abdominal pain. ConclusionSBRT to AGM achieved a satisfactory local control and OS in oligometastatic patients. High minimum PTV dose and BED10 prescription doses were predictive of improved LR and OS, respectively. Prospective studies are needed to determine comprehensive criteria for patients SBRT eligibility and dosimetric planning.

Highlights

Since its first use in the treatment of extracranial tumors in the early 1990s, stereotactic body radiotherapy (SBRT) has been explored and validated in a myriad of disease sites and settings [1]
On univariable analysis (UVA), primary small cell lung cancer (SCLC) was correlated with poor local recurrence-free survival (LRFS) (p = 0.026), and a minimum PTV dose above a BED10 of 46 Gy (p = 0.061) was correlated with improved LRFS
This correlation remained statistically significant for SCLC (HR 15.3, 95%CI 3.8–61.4, p = 0.00012) and minimum PTV dose above a BED10 of 46 Gy (HR 0.37, 95%CI 0.18–0.76, p = 0.0064) on multivar iable (MVA) analysis (Fig. 2A, 2C, 2E)

Summary

Introduction

Since its first use in the treatment of extracranial tumors in the early 1990s, stereotactic body radiotherapy (SBRT) has been explored and validated in a myriad of disease sites and settings [1]. Many of the oligometastatic patients with AGM are not candidate for adrenalectomy [16] due to limited performance status [17], the pres ence of more than one metastatic site [16], and to the associated suboptimal prognosis [17]. Studies reporting SBRT outcomes in oligometastatic patients with adrenal gland metastases (AGM) are limited. We present a multi-institutional analysis of oligometastatic patients treated with SBRT for AGM. Among CORE patients, those treated with SBRT for AGM were included. A minimum PTV dose BED10 > 46 Gy was associated with an improved OS and LRFS. Conclusion: SBRT to AGM achieved a satisfactory local control and OS in oligometastatic patients. Prospective studies are needed to determine comprehensive criteria for patients SBRT eligibility and dosimetric planning

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Conclusion