The Effect of Prescription Isodose Variation on Tumor Control and Toxicities in Stereotactic Radiosurgery for Sporadic Vestibular Schwannoma: Propensity Score-Matched Case–Control Study

Abstract

Objective Vestibular schwannoma (VS) treated with Gamma Knife stereotactic radiosurgery (SRS) was typically performed at 50% isodose line (IDL50); however, the impact of IDL variation on outcomes is poorly understood. This study aimed to compare tumor control (TC) and toxicities between treatment at 40% (IDL40) and 50% (IDL50).

Methods Sporadic/unilateral VS patients treated with SRS dose 12 to 14 Gy and prescription isodose volume ≤10cm³ were included. Propensity score matching was applied to IDL40 cohort to generate an IDL50 companion cohort, adjusting for age and prescription isodose volume. After exclusion of patients with follow-up <24 months, there were 30 and 28 patients in IDL40 and IDL50 cohorts, respectively.

Results Median follow-up time was 96 months (24–225 months). Actuarial and radiographic TC rates were 91.8% and clinical TC was 96.2% both at 5 and 10 years. TC was higher in IDL40 cohort but not significant (96.4 vs. 86.7%; p = 0.243). Hearing preservation (HP) rates were 71.9 and 39.2% at 5- and 10-year intervals, with significantly higher rates of HP noted in IDL40 cohort (83.3 vs. 57.1% at 5-year interval; 62.5 vs. 11.4% at 10-year interval; p = 0.017). Permanent facial neuropathy occurred in two patients, both from the IDL50 cohort (3.5%). Rates of post-SRS steroid treatment or shunt placement for hydrocephalus were slightly higher in IDL50 patients (6.9 vs. 17.9%; p = 0.208 and 3.3 vs. 7.1%; p = 0.532).

Conclusion For treatment of VS with SRS, dose prescription at IDL40 or IDL50 provides excellent long-term TC and toxicity profiles. IDL40 may be associated with improved long-term HP.

Keywords

vestibular schwannoma - acoustic neuroma - radiosurgery - Gamma Knife - isodose line - hearing preservation - facial neuropathy - propensity score matched

Note

This study was presented as a poster presentation at the 24^th Annual Meeting Society for NeuroOncology, Phoenix, Arizona, November 22th to 24th, 2019.

Ethics

IRB Application number 19–002719, approval date 4/15/2019.

Publication History

Received: 05 April 2020

Accepted: 03 September 2020

Article published online:
18 February 2021

• References

• 1 Boari N, Bailo M, Gagliardi F. et al. Gamma Knife radiosurgery for vestibular schwannoma: clinical results at long-term follow-up in a series of 379 patients. J Neurosurg 2014; 121 (Suppl): 123-142
• 2 Carlson ML, Jacob JT, Pollock BE. et al. Long-term hearing outcomes following stereotactic radiosurgery for vestibular schwannoma: patterns of hearing loss and variables influencing audiometric decline. J Neurosurg 2013; 118 (03) 579-587
• 3 Chopra R, Kondziolka D, Niranjan A, Lunsford LD, Flickinger JC. Long-term follow-up of acoustic schwannoma radiosurgery with marginal tumor doses of 12 to 13 Gy. Int J Radiat Oncol Biol Phys 2007; 68 (03) 845-851
• 4 Chung WY, Liu KD, Shiau CY. et al. Gamma Knife surgery for vestibular schwannoma: 10-year experience of 195 cases. J Neurosurg 2005; 102 (Suppl): 87-96
• 5 Flickinger JC, Kondziolka D, Niranjan A, Lunsford LD. Results of acoustic neuroma radiosurgery: an analysis of 5 years' experience using current methods. J Neurosurg 2001; 94 (01) 1-6
• 6 Flickinger JC, Kondziolka D, Niranjan A, Maitz A, Voynov G, Lunsford LD. Acoustic neuroma radiosurgery with marginal tumor doses of 12 to 13 Gy. Int J Radiat Oncol Biol Phys 2004; 60 (01) 225-230
• 7 Fukuoka S, Takanashi M, Hojyo A, Konishi M, Tanaka C, Nakamura H. Gamma Knife radiosurgery for vestibular schwannomas. Prog Neurol Surg 2009; 22: 45-62
• 8 Hasegawa T, Kida Y, Kato T, Iizuka H, Kuramitsu S, Yamamoto T. Long-term safety and efficacy of stereotactic radiosurgery for vestibular schwannomas: evaluation of 440 patients more than 10 years after treatment with Gamma Knife surgery. J Neurosurg 2013; 118 (03) 557-565
• 9 Kano H, Kondziolka D, Khan A, Flickinger JC, Lunsford LD. Predictors of hearing preservation after stereotactic radiosurgery for acoustic neuroma. J Neurosurg 2009; 111 (04) 863-873
• 10 Klijn S, Verheul JB, Beute GN. et al. Gamma Knife radiosurgery for vestibular schwannomas: evaluation of tumor control and its predictors in a large patient cohort in The Netherlands. J Neurosurg 2016; 124 (06) 1619-1626
• 11 Lee GY, Roos DE, Brophy BP. Radiosurgery for vestibular schwannomas: preliminary results of the Adelaide experience. Stereotact Funct Neurosurg 2001; 76 (3-4): 209-212
• 12 Lunsford LD, Niranjan A, Flickinger JC, Maitz A, Kondziolka D. Radiosurgery of vestibular schwannomas: summary of experience in 829 cases. J Neurosurg 2005; 102 (Suppl): 195-199
• 13 Pollock BE, Link MJ, Foote RL. Failure rate of contemporary low-dose radiosurgical technique for vestibular schwannoma. J Neurosurg 2009; 111 (04) 840-844
• 14 Rueß D, Pöhlmann L, Hellerbach A. et al. Acoustic neuroma treated with stereotactic radiosurgery: follow-up of 335 patients. World Neurosurg 2018; 116: e194-e202
• 15 Tucker DW, Gogia AS, Donoho DA. et al. Long-term tumor control rates following Gamma Knife radiosurgery for acoustic neuroma. World Neurosurg 2019; 122: 366-371
• 16 Watanabe S, Yamamoto M, Kawabe T. et al. Stereotactic radiosurgery for vestibular schwannomas: average 10-year follow-up results focusing on long-term hearing preservation. J Neurosurg 2016; 125 (Suppl. 01) 64-72
• 17 Wowra B, Muacevic A, Fürweger C, Schichor C, Tonn JC. Therapeutic profile of single-fraction radiosurgery of vestibular schwannoma: unrelated malignancy predicts tumor control. Neuro-oncol 2012; 14 (07) 902-909
• 18 Committee on Hearing and Equilibrium guidelines for the evaluation of hearing preservation in acoustic neuroma (vestibular schwannoma). American Academy of Otolaryngology-Head and Neck Surgery Foundation, INC. Otolaryngol Head Neck Surg 1995; 113 (03) 179-180
• 19 Paddick I, Lippitz B. A simple dose gradient measurement tool to complement the conformity index. J Neurosurg 2006; 105 (Suppl): 194-201
• 20 Lees KA, Tombers NM, Link MJ. et al. Natural history of sporadic vestibular schwannoma: a volumetric study of tumor growth. Otolaryngol Head Neck Surg 2018; 159 (03) 535-542
• 21 Li D, Tsimpas A, Germanwala AV. Analysis of vestibular schwannoma size: a literature review on consistency with measurement techniques. Clin Neurol Neurosurg 2015; 138: 72-77
• 22 van de Langenberg R, de Bondt BJ, Nelemans PJ, Baumert BG, Stokroos RJ. Follow-up assessment of vestibular schwannomas: volume quantification versus two-dimensional measurements. Neuroradiology 2009; 51 (08) 517-524
• 23 Friedman WA, Bradshaw P, Myers A, Bova FJ. Linear accelerator radiosurgery for vestibular schwannomas. J Neurosurg 2006; 105 (05) 657-661
• 24 Mahboubi H, Sahyouni R, Moshtaghi O. et al. CyberKnife for treatment of vestibular schwannoma: a meta-analysis. Otolaryngol Head Neck Surg 2017; 157 (01) 7-15
• 25 Kondziolka D, Lunsford LD, McLaughlin MR, Flickinger JC. Long-term outcomes after radiosurgery for acoustic neuromas. N Engl J Med 1998; 339 (20) 1426-1433
• 26 Norén G, Greitz D, Hirsch A, Lax I. Gamma Knife surgery in acoustic tumours. Acta Neurochir Suppl (Wien) 1993; 58: 104-107
• 27 Okunaga T, Matsuo T, Hayashi N. et al. Linear accelerator radiosurgery for vestibular schwannoma: measuring tumor volume changes on serial three-dimensional spoiled gradient-echo magnetic resonance images. J Neurosurg 2005; 103 (01) 53-58
• 28 Pollock BE. Management of vestibular schwannomas that enlarge after stereotactic radiosurgery: treatment recommendations based on a 15 year experience. Neurosurgery 2006; 58 (02) 241-248 , discussion 241–248
• 29 Yu CP, Cheung JY, Leung S, Ho R. Sequential volume mapping for confirmation of negative growth in vestibular schwannomas treated by Gamma Knife radiosurgery. J Neurosurg 2000; 93 (Suppl. 03) 82-89
• 30 Carlson ML, Vivas EX, McCracken DJ. et al. Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on hearing preservation outcomes in patients with sporadic vestibular schwannomas. Neurosurgery 2018; 82 (02) E35-E39
• 31 Yang I, Aranda D, Han SJ. et al. Hearing preservation after stereotactic radiosurgery for vestibular schwannoma: a systematic review. J Clin Neurosci 2009; 16 (06) 742-747
• 32 Yang I, Sughrue ME, Han SJ. et al. A comprehensive analysis of hearing preservation after radiosurgery for vestibular schwannoma. J Neurosurg 2010; 112 (04) 851-859
• 33 Sughrue ME, Yang I, Han SJ. et al. Non-audiofacial morbidity after Gamma Knife surgery for vestibular schwannoma. Neurosurg Focus 2009; 27 (06) E4
• 34 Yang I, Sughrue ME, Han SJ. et al. Facial nerve preservation after vestibular schwannoma Gamma Knife radiosurgery. J Neurooncol 2009; 93 (01) 41-48
• 35 Liscak RNJ, Urgosik D, Vladyka V, Simonova G. Statistical analysis of risk factors after Gamma Knife radiosurgery of acoustic neurinomas. Radiosurgery 2000; 3: 205-213