Stereotactic Radiosurgery for Glomus Jugulare Tumors: Long-Term Tumor Control Using 3D Volumetric Tumor Analysis

Objective: Traditionally, management of jugular paraganglioma (JP) involved an aggressive attempt at gross-total resection, in part due to the perceived radioresistance of these tumors. The morbidity of such approaches was often severe, often resulting in profound dysphagia and dysphonia from lower cranial nerve injury. Since 1990, stereotactic radiosurgery (SRS) has been employed in the treatment of JP and other benign skull base pathologies at our institution. Due to their infiltrative growth pattern and irregular shape, conventional means of assessing progression using linear or elliptical approximations of size are imprecise. Herein we present long-term tumor control and cranial nerve outcomes in patients treated with SRS for JP at our institution, utilizing slice-by-slice 3D volumetric segmentation of MRI data to assess radiographic control.

Methods: Radiographic data and patient records were reviewed at a single, tertiary care referral center for patients treated from 1990 to 2017. Volumetric analyses of serial MRI data were performed by integrating consecutive tumor cross-sectional areas. Radiographic progression was defined as volumetric growth of 15% or greater over the imaging follow-up interval. Primary outcomes included survival free of radiographic or clinical progression and new or worsened cranial neuropathy, determined by overall ratio and assessment of functioning nerves at risk by treatment approach.

Results: A total of 85 patients with JP were treated with Gamma Knife radiosurgery (GKRS) at our institution during the study period. Sixty patients had pre- and posttreatment contrast-enhanced MRI studies suitable for volumetric analysis. A total of 214 MR images were analyzed to assess tumor volumes in a slice-by-slice manner. Median follow-up was 66 months (range 7–202 months). Three tumors exhibited progression greater than 10 years following GKRS. Estimated survival free of radiographic progression rates (95% confidence interval [CI]; n = number still at risk) at 5, 10, and 15 years following radiosurgery were 98% (95% CI: 94–100%; n = 34), 94% (95% CI: 85–100%; n = 16), and 74% (95% CI: 56–98%; n = 6), respectively. One patient with radiographic progression required treatment with external beam radiation therapy, constituting the only case of clinical progression. There were no new cases of facial or lower cranial neuropathy following primary GKRS. Of 82 patients with available clinical follow-up data, two patients (2.4%) developed new or worsened cranial nerve 10 dysfunction, manifest in ipsilateral vocal fold immobility.

Conclusion: Stereotactic radiosurgery achieves excellent long-term tumor control for JP. Volumetric segmentation provides a precise means of assessing radiographic progression of ill-defined tumors such as JP. The risk of new or worsened cranial neuropathy following GKRS in primary, combined modality (i.e., following intentional subtotal resection), or recurrent settings is low. As 3 patients in this series exhibited progression at greater than 10 years following GKRS, long-term follow-up is critical. However, as none of these patients required salvage therapy, the clinical significance of this degree of radiographic progression has yet to be determined.