Abstract
The efficacy of radiosurgery for neurofibromatosis type 2 (NF2)-associated vestibular schwannoma (VS) remains debatable. We retrospectively analyzed radiosurgical outcomes for NF2-associated VS compared to sporadic VS using our database of 422 consecutive VS patients. Twenty-five patients with 30 NF2-associated VSs with a mean follow-up of 121 months were identified. NF2-associated VSs exhibited excellent tumor control (10-year cumulative rate, 92% vs. 92% in sporadic VSs; p = 0.945) and worse overall survival (73% vs. 97%; p = 0.005), mainly due to tumor progression other than the treated VSs. The presence of NF2 was not associated with failed tumor control via multivariate Cox proportional hazard analyses. No difference in radiation-induced adverse events (RAEs) was confirmed between cohorts, and prescription dose (hazard ratio 8.30, 95% confidence interval 3.19–21.62, p < 0.001) was confirmed as a risk for cranial nerve injuries via multivariate analysis. Further analysis after propensity score matching using age, volume, and sex as covariates showed that NF2-associated VSs exhibited excellent local control (100% vs. 93%; p = 0.240) and worse overall survival (67% vs. 100%; p = 0.002) with no significant difference in RAEs. Excellent long-term tumor control and minimal invasiveness may make radiosurgery a favorable therapeutic option for NF2 patients with small to medium VS, preferably with non-functional hearing or deafness in combination with postoperative tumor growth or progressive non-operated tumors, or with functional hearing by patients’ wish.
Highlights
Neurofibromatosis type 2 (NF2) is a rare autosomal dominant genetic disorder caused by inactivating alterations in the neurofibromatosis type 2 (NF2) gene on chromosome 22q12.2, with a prevalence of around 1 in60,000 [1,2,3,4]
The present study showed excellent progression-free rates (PFRs) (92% at 10–20 years) for NF2-associated vestibular schwannomas (VS), even though we had used relatively low radiosurgical doses, with these results bolstered by our long-term observation period
While some earlier studies reported that outcomes of NF2-associated VSs were inferior to those of sporadic VSs [19,20,22,23,29]. the two most recent studies found no difference [17,24]
Summary
Neurofibromatosis type 2 (NF2) is a rare autosomal dominant genetic disorder caused by inactivating alterations in the NF2 gene on chromosome 22q12.2, with a prevalence of around 1 in60,000 [1,2,3,4]. Patients with NF2 develop multiple tumors in the nervous system, and NF2-associated tumors often contribute to earlier-than-expected death [5]. VSs are the most common cause of morbidity, potentially resulting in bilateral sensorineural hearing loss, tinnitus, balance difficulty, and deafness, facial nerve weakness, and possible brainstem compression [8,9]. Stereotactic radiosurgery (SRS) is a main therapeutic modality for small to medium-large sporadic VS, offering advantages such as excellent tumor control, low toxicity for the facial nerve, and minimal invasiveness [11,12,13,14,15,16]. Robust evidence regarding the use of SRS for NF2-associated VSs is lacking, and long-term outcomes have not been fully elucidated [17,18,19,20,21,22,23,24,25,26,27]
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