(P010) Stereotactic Body Radiotherapy for Treatment of Adrenal Gland Metastasis: Toxicity, Outcomes, and Patterns of Failure

William W. Chance, MD, Quynh-Nhu Nguyen, MD, Reza J. Mehran, MD, James W. Welsh, MD, Daniel R. Gomez, MD, Peter A. Balter, PhD, Ritsuko Komaki, MD, Zhongxing Liao, MD, Joe Y. Chang, MD, PhD; UT MD Anderson Cancer Center

PURPOSE: A single-institution, retrospective review of toxicity, patterns of failure, and outcomes in patients undergoing stereotactic body radiotherapy (SBRT) for metastasis to the adrenal gland.

MATERIALS AND METHODS: From 2009–2014, a total of 36 patients with 40 adrenal metastases were treated with SBRT. The median age of the patient population was 63.7 years (range: 50–77 yr). Primary sites included lung (n = 31), ovary (n = 2), bladder (n = 1), esophagus (n = 1), and melanoma (n = 1). A total of 32 patients received treatment to a single adrenal gland, while 4 patients received treatment to the bilateral adrenal glands. The prescription dose to the target was 60 Gy in 10 fractions (n = 25), 50 Gy in 10 fractions (n = 10), 50 Gy in 4 fractions (n = 4), or other (n = 4). Failures within the prescribed high-dose irradiated region were considered local failures. New or progressive distant metastases outside of the treated adrenal gland were considered distant failures. After review of the radiation treatment plan, local failures were characterized as in-field (epicenter within the 100% isodose line) or marginal (between the 50% and 100% isodose lines).

RESULTS: Median follow-up was 12.6 months after radiation treatment (range: 1.4–37.1 mo). Six patients developed grade 1 gastrointestinal toxicity. Two patients who were treated to the bilateral adrenal glands developed grade 2 adrenal insufficiency. There was no grade 3 or 4 toxicity observed. Median overall survival after treatment was 19.5 months. The 1- and 2-year overall survival rates were 67% and 55%, respectively. The 1-year freedom from local failure was 87%. The median time to local failure was not reached. The 1-year freedom from disease progression was 25% (median time to progression, 5.9 mo). The 1-year freedom from distant failure was 33% (median time to distant failure, 6.0 mo). There were six in-field local failures and one marginal failure observed.

CONCLUSION: SBRT is an effective treatment modality, achieving excellent local control with minimal toxicity for patients with adrenal metastases. The development of progressive distant metastasis is the predominant pattern of failure affecting patients’ survival outcomes.

Proceedings of the 97th Annual Meeting of the American Radium Society - americanradiumsociety.org