Single institution experience treating adrenal metastases with stereotactic body radiation therapy

Objective: The objective of the study is to present our experience of treating adrenal metastases using stereotactic body radiation therapy (SBRT). Materials and Methods: We retrospectively reviewed patients with adrenal metastases treated using SBRT from 2001 to 2014. Response Evaluation Criteria in Solid Tumors v1.1 was used. Maximum tumor response was defined as the greatest percentage tumor reduction noted on two or more post-SBRT CT scans. Results: We identified 44 patients (median age 61.3 years, range: 25.8-85), with 54 adrenal metastases; primary diagnoses include non-small cell lung cancer (28 patients and 38 lesions), small cell lung cancer (1 patient), hepatocellular carcinoma (6 patients), and other (9 patients). Treatment was delivered in single (16 lesions, median dose 18 Gy [14-18]) or multiple fractions (38 lesions, median dose 30 Gy [16-40]). Median planning target volume was 49.65cc (3.21-984.54). Median response at first post-SBRT follow-up (median 1.65 months (m) (0.33-5.37), n = 46 lesions) was 10.8% with 91.3% local control. Median maximum tumor response was 31.8% (n = 32 lesions) at median follow-up of 5.4 m (0.9-44.8) with 96.6% local control. The response was comparable regardless of tumor histology or treatment fractionation. No patients experienced Grade 3/4 acute toxicities. One patient with a history of naproxen use required suturing with omental patch placement for perforated pyloric ulcer 14 m post-SBRT (18 Gy in single fraction) to the right adrenal metastasis; this region received <5 Gy. Ten patients treated for pain with available follow-up obtained relief. Conclusions: SBRT is a safe and efficacious treatment for adrenal metastases, demonstrating local tumor control. Further study of the impact on survival and quality of life is warranted.