Spine Stereotactic Radiosurgery for Metastatic Pheochromocytoma.

Shane Mesko,Neil M D'Souza,Xin A Wang,Brian J Deegan,Bhavana V Chapman,Jing Li,Behrang Amini,Paul D Brown,Claudio E Tatsui,Mary Frances Mcaleer,Laurence Rhines,Amol J Ghia

doi:10.7759/cureus.4742

Shane Mesko, Neil M D'Souza + Show 10 more

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https://doi.org/10.7759/cureus.4742

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Abstract

Purpose: Despite aggressive primary treatment, up to 13.5% of patients diagnosed with pheochromocytoma may develop metastases, most often affecting the axial skeleton. Given that systemic therapy options are often inadequate, local therapy remains the cornerstone of palliation for these patients. Historically poor responses to standard fractionated radiotherapy have led to the consideration of stereotactic radiosurgery as an option to overcome potential radioresistance and provide durable local control of these tumors. Here we report our institutional experience in treating spine metastases from pheochromocytoma with spine stereotactic radiosurgery (SSRS).Methods and materials: Our clinical databases were retrospectively reviewed for patients with metastatic pheochromocytoma treated with SSRS from 2000-2017. Seven patients with 16 treated metastatic spinal lesions were identified. Local control was evaluated using magnetic resonance imaging (MRI). Pain and symptom data were assessed to evaluate toxicity using Common Terminology Criteria for Adverse Events (CTCAE) v4.03. The Kaplan-Meier method was used to assess local control and overall survival (OS).Results: Median follow-up for treated lesions was 11 months (range 2.2 - 70.8). Most lesions were treated to a dose of 27 Gy in three fractions (62.5%). Other fractionation schemes included 24 Gy in one fraction (25%), 16 Gy in one fraction (6.3%), and 18 Gy in three fractions (6.3%). Treatment sites included the cervical spine (18.8%), thoracic spine (37.5%), lumbar spine (31.3%), and sacrum (12.5%). The crude local control rate was 93.7%, with one thoracic spine lesion progressing 20.7 months after treatment with 24 Gy in one fraction. Kaplan-Meier OS rates at 1 and 2 years after SSRS were 71.4% and 42.9%, respectively. Most common toxicities included acute grade 1-2 pain and fatigue. There was one case of vertebral fracture in a cervical spine lesion treated to 27 Gy in three fractions, which was managed non-surgically.Conclusion: Very few studies have explored the use of SSRS in metastatic pheochromocytoma. Our data suggest this modern radiation modality is effective, safe, and provides durable local control to palliate symptoms and potentially limit further metastatic seeding. Larger patient numbers and longer follow-up will further define the role of SSRS as a treatment option in these patients.

Highlights

Pheochromocytoma is a catecholamine-secreting tumor originating from chromaffin cells in the adrenal medulla and belongs to the intra-adrenal subcategory of paragangliomas (PGLs) [12]
All patients were of good performance status at the time of radiation treatment with a median Karnofsky Performance Status (KPS) of 90
A recent review of 17 patients with metastases of pheochromocytoma in the thorax, abdomen, or pelvis who were treated with a variety of modern radiotherapy techniques, including intensity modulated radiation therapy (IMRT), showed external beam radiation therapy (EBRT) to be effective for local control and symptomatic relief in 76% of patients especially in conjunction with I131-MIBG in cases of bulky tumors [26]

Summary

Introduction

Pheochromocytoma is a catecholamine-secreting tumor originating from chromaffin cells in the adrenal medulla and belongs to the intra-adrenal subcategory of paragangliomas (PGLs) [12]. Pheochromocytomas are rare with only 1-6 cases per million people per year, and approximately 13.5% of these are found to be metastatic [3,4,5]. Five-year survival for metastatic disease ranges from 34% to 60%, depending largely on organ involvement, compared to 90% to 95% survival rates for benign disease [6]. Surgery remains the mainstay of therapy for both benign and malignant disease. Recurrence rates for metastatic disease are high even after resection, and the goals of therapy are often geared toward palliation of symptoms [10]. Iodine131-labeled metaiodobenzylguanidine (I131-MIBG) has shown utility as an adjunct to surgery [9,11]. Systemic therapy, including chemotherapy with cyclophosphamide, vincristine, and dacarbazine (CVD), has shown short-lived benefit, while targeted therapies directed against vascular endothelial growth factor (VEGF) and platelet-derived growth factor receptors (PDGFR) are under investigation [2,12]

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