NCOG-12. STEREOTACTIC RADIOSURGERY FOR VESTIBULAR SCHWANNOMAS IN NEUROFIBROMATOSIS TYPE 2 PATIENTS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract

Abstract BACKGROUND One of the hallmarks of neurofibromatosis type 2 (NF2) is the presence of bilateral vestibular schwannomas (VSs) that result in progressive hearing loss and compression of nearby brainstem structures causing cranial nerve palsies. Treatment of these tumors remains challenging, as both surgical removal and expectant management can result in symptom progression. Stereotactic radiosurgery (SRS) has recently been investigated for the management of NF2-associated VSs; however, the role, promises, and pitfalls of this treatment modality remain unclear. METHODS Ovid MEDLINE, EMBASE, Web of Science, and Cochrane Reviews were searched for studies assessing SRS outcome in NF2-associated VSs only. Primary endpoints included tumor control, serviceable hearing, presence of tinnitus, and cranial nerve V and VII symptoms. RESULTS A total of 16 studies (589 patients harboring 750 tumors) was included in this analysis. Clinical tumor control was achieved in 88% of cases (95% CI: 80%-95%); salvage surgery was needed in 8% (95% CI: 4%-13%) of cases. Treatment resulted in a worsening of pre-treatment serviceable hearing (OR of 0.26, p < 0.01), in an increase of facial nerve impairment (OR of 1.62, p < 0.01), and showed a trend for increase trigeminal nerve impairment as well (OR of 1.42, p = 0.07). The incidence of vestibular symptoms and hydrocephalus requiring shunting could not be assessed since these measures were not reported consistently. CONCLUSIONS The treatment of NF2-associated VS continues to pose a challenge, as current SRS regimens result in impaired hearing and worse cranial nerve comorbidities, despite achieving high tumor control. It remains unclear if these findings have to be intended as treatment complications or, rather, continuous disease progression despite tumor control.