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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 ≤10cm 3 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.
摘要：
目的伽玛刀立体定向放射外科（SRS）治疗的前庭神经鞘瘤（VS）通常在50％等剂量线（IDL50）进行；然而，IDL变异对结局的影响知之甚少.本研究旨在比较40%(IDL40)和50%(IDL50)治疗之间的肿瘤对照(TC)和毒性。方法纳入接受SRS剂量12至14Gy和处方等剂量≤10cm3治疗的散发性/单侧VS患者。将倾向评分匹配应用于IDL40队列以生成IDL50同伴队列，调整年龄和处方剂量。排除术后随访<24个月的患者，IDL40和IDL50队列中有30和28名患者，分别。结果中位随访时间为96个月(24～225个月)。在5年和10年时，精算和影像学TC率为91.8％，临床TC为96.2％。IDL40队列中TC较高，但不显着（96.4与86.7%；p=0.243）。5年和10年的听力保留率（HP）分别为71.9％和39.2％，在IDL40队列中，HP的发生率明显较高(83.3vs.5年间隔57.1%；62.5vs.10年间隔为11.4%；p=0.017)。两名患者发生永久性面神经病变，两者均来自IDL50队列(3.5%)。在IDL50患者中，SRS后类固醇治疗或分流术治疗脑积水的比率略高（6.9vs.17.9%；p=0.208和3.3vs.7.1%；p=0.532）。结论SRS治疗VS,IDL40或IDL50的剂量处方可提供出色的长期TC和毒性特征。IDL40可以与改善的长期HP相关联。
