2026 Proffered Presentations
S128: COMPARATIVE ANALYSIS OF FSRT AND SRS FOR VESTIBULAR SCHWANNOMA USING A LARGE MULTI-INSTITUTIONAL DATASET
Ian Argento1; Daniel Uralov, Dr2; Jacob Beiriger, Dr1; Anika Walia2; Kalena Liu2; Wenyin Shi, Dr2; Jacob Hunter, Dr2; 1Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA; 2Department of Otolaryngology - Head and Neck Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
Background: Treatment of vestibular schwannomas (VS) aims to control tumor growth, while preserving hearing and facial nerve function. Radiation options include stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT). Both achieve high tumor control, but their relative impact on functional outcomes remains uncertain. Prior studies are limited by small sample sizes and heterogeneous methods.
Methods: Deidentified data from 100 healthcare organizations were collected using the TriNetX platform. Adults with vestibular schwannomas, coded as benign cranial neoplasms and sensorineural hearing loss (ICD-10: D33.3 and H90.A/H90.1–H90.8), were included. Patients with neurofibromatosis (ICD-10: Q85.00–Q85.02) and those who underwent surgical resection (CPT: 61616, 6159x) were excluded. Patients were grouped by treatment: one session of SRS (CPT: 77371, 77372; HCPCS: G0339) or two or more sessions of FSRT (CPT: 77373, 77435, 77427; HCPCS: G0340).
Propensity score matching (1:1) yielded 909 patients per cohort. Outcomes and frequency of outcomes including symptom recurrence, cerebral edema, hydrocephalus, and cranial nerve damage were evaluated at 1-, 5-, 10-, and 15-years post-treatment. Aside from hearing loss (an inclusion criterion), patients experiencing any outcomes prior to radiation were excluded. Age effects were assessed by comparing 10-year hearing loss rates among patients treated at ages 0–55, 56–65, or 66–90. A meta-regression analysis tested for a linear trend between patient age group and the effect size of FSRT vs SRS on hearing loss. Finally, we conducted a subgroup analysis of 2-5 sessions and 5+ sessions of FSRT compared to SRS.
Results: At 15-years post-treatment, the FSRT cohort exhibited a lower risk for hearing loss (Risk Difference: -9.4% [0.481 vs 0.574]; p<0.001), but a higher risk for cerebral edema (Risk Difference: +2.6% [0.037 vs 0.021]; p= 0.003). Most events of hearing loss occurred within one year of treatment while most events of cerebral edema occurred within the first five years. No differences were observed in symptom frequency or in rates of tinnitus, facial nerve dysfunction, trigeminal neuropathy, vestibular dysfunction, hydrocephalus, ataxia, or diplopia. Hearing outcomes were similar between FSRT subgroups (Relative Risk of 2-5 sessions: 0.877; RR of 5+ sessions: 0.836). Too few patients experienced cerebral edema in the 2-5 sessions of FSRT cohort to report effect sizes, though the 5+ session cohort had a smaller effect size than the pooled FSRT cohort (Relative Risk of 5+ sessions: 1.854; RR of pooled FSRT: 2.229). At 10 years, meta regression analysis revealed no significant trend between age-group and treatment effect size on hearing loss (β = - 0.0095, p = 0.789), suggesting that FSRT’s lower risk is consistent across age strata.
Conclusion: Compared to SRS, FSRT was associated with lower long-term risks of hearing loss at the cost of a small increase in cerebral edema. Age and number of FSRT sessions did not influence the effect size of hearing preservation. These findings support future research to guide patient-specific treatment selection in vestibular schwannoma.