(P112) Spine Stereotactic Radiosurgery in the Treatment of Metastatic Pheochromocytoma: A Case Series

April 30, 2015

Our data suggest that SSRS is an effective, safe, and durable treatment option. Given the robust tumor control of SSRS and the possibility for metastatic foci to serve as sources for further systemic spread, proactive treatment of spinal metastasis earlier in the disease course may offer therapeutic benefit to these patients.

Brian J. Deegan, MD, PhD, Amol J. Ghia, MD, Mary Frances McAleer, MD, PhD, Xin A. Wang, PhD, Paul D. Brown, MD, Jing Li, MD, PhD; UT MD Anderson Cancer Center

PURPOSE: Metastasis occurs in approximately 10% of all cases of pheochromocytoma and can cause significant morbidity and mortality. The axial skeleton is the most frequent site of these metastases. Since good systemic therapy options are lacking, local therapy remains the cornerstone of palliation for many of these patients. Due to the poor response of pheochromocytoma to standard fractionated radiotherapy, stereotactic radiosurgery (SRS) is an attractive option to overcome potential radioresistance and provide more durable local control (LC) of these tumors. Here, we report our institutional experience in the treatment of spine metastases from pheochromocytoma with spine SRS (SSRS).

METHODS: The available records of patients with metastatic pheochromocytoma treated with SSRS between 2000 and 2014 were retrospectively reviewed. Four patients with nine treated metastatic spinal lesions were identified. Follow-up spine magnetic resonance imaging (MRI) was used to evaluate LC. Pain and symptom data were assessed to evaluate toxicity. Kaplan-Meier method was used to assess LC and overall survival (OS).

RESULTS: Median age at time of SSRS was 55 years (range: 46–63 yr). Median follow-up for each treated site was 11 months (range: 4.5–54.6 mo). Treated areas included C-spine (22%), T-spine (33%), L-spine (33%), and sacrum (11%). The most common fractionation scheme was 27 Gy in three fractions (55.6%), followed by 24 Gy in one fraction (22.2%), 16 Gy in one fraction (11.1%), and 18 Gy in three fractions (11.1%). Crude LC rate was 100%, with no local treatment failures observed in the follow-up period. There were two patient deaths in the group (50%). The Kaplan-Meier OS from SSRS at 1 year was 75% and 50% at 2 years. Median time to SSRS from metastatic presentation was 17.6 months (range: 9.2–72.7 mo). Toxicities included pain (two cases), fatigue (two cases), and vertebral fracture (one case).

CONCLUSION: To our knowledge, this work is the first study describing the utility of SSRS in the treatment of metastatic pheochromocytoma. Our data suggest that SSRS is an effective, safe, and durable treatment option. Given the robust tumor control of SSRS and the possibility for metastatic foci to serve as sources for further systemic spread, proactive treatment of spinal metastasis earlier in the disease course may offer therapeutic benefit to these patients. Larger patient numbers and longer follow-up are required to address this issue more fully.

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