Stereotactic or conformal radiotherapy for adrenal metastases: Patient characteristics and outcomes in a multicenter analysis

Abstract

To report outcome (freedom from local progression [FFLP], overall survival [OS] and toxicity) after stereotactic, palliative or highly conformal fractionated (>12) radiotherapy (SBRT, Pall‐RT, 3DCRT/IMRT) for adrenal metastases in a retrospective multicenter cohort within the framework of the German Society for Radiation Oncology (DEGRO). Adrenal metastases treated with SBRT (≤12 fractions, biologically effective dose [BED10]\u2009≥\u200950\u2009Gy), 3DCRT/IMRT (>12 fractions, BED10\u2009≥\u200950\u2009Gy) or Pall‐RT (BED10\u2009<\u200950\u2009Gy) were eligible for this analysis. In addition to unadjusted FFLP (Kaplan‐Meier/log‐rank), we calculated the competing‐risk‐adjusted local recurrence rate (CRA‐LRR). Three hundred twenty‐six patients with 366 metastases were included by 21 centers (median follow‐up: 11.7 months). Treatment was SBRT, 3DCRT/IMRT and Pall‐RT in 260, 27 and 79 cases, respectively. Most frequent primary tumors were non‐small‐cell lung cancer (NSCLC; 52.5%), SCLC (16.3%) and melanoma (6.7%). Unadjusted FFLP was higher after SBRT vs Pall‐RT (P = .026) while numerical differences in CRA‐LRR between groups did not reach statistical significance (1‐year CRA‐LRR: 13.8%, 17.4% and 27.7%). OS was longer after SBRT vs other groups (P\u2009<\u2009.05) and increased in patients with locally controlled metastases in a landmark analysis (P\u2009<\u2009.0001). Toxicity was mostly mild; notably, four cases of adrenal insufficiency occurred, two of which were likely caused by immunotherapy or tumor progression. Radiotherapy for adrenal metastases was associated with a mild toxicity profile in all groups and a favorable 1‐year CRA‐LRR after SBRT or 3DCRT/IMRT. One‐year FFLP was associated with longer OS. Dose‐response analyses for the dataset are underway.