2026 Poster Presentations
P099: POPULATION-BASED SURVIVAL ANALYSIS ON PATIENTS WITH MALIGNANT PERIPHERAL NERVE SHEATH TUMORS OF THE EIGHTH NERVE
Abhishek Bhutada, MD; Kristine Ravina, MD; Srijan Adhikari, MD; Austin Hoggarth, MD; Eric Marvin, DO; Carilion Clinic
Background: Malignant vestibular schwannomas or malignant peripheral nerve sheath tumors of the eighth nerve are exceedingly rare and associated with poor prognosis. Data in the literature thus far is scarce and mostly consists of case reports. To better understand the prognosis and survival predictors, we performed a population-based analysis of demographic and treatment-related factors.
Methods: From 2000 to 2020, all patients with malignant tumors of the eighth cranial nerve were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Selection criteria included patients with only malignant behavior tumors that were in primary site code ‘C72.4-Acoustic Nerve’ and were classified either as malignant neurilemmomas or malignant peripheral nerve sheath tumors. Kaplan–Meier method was used to estimate overall survival (OS), and Cox proportional hazards regression was applied for univariate and multivariable analyses. Survival by age and treatment modality was visualized with Kaplan–Meier plots.
Results: A total of 38 patients were included in the analysis. The overall 1-, 2-, and 5-year survival was 79%, 77%, and 68%, respectively. Sex distribution showed 22 females and 16 males and was not significantly associated with OS (HR 1.3, 95% CI 0.5–3.6, p=0.5). Median age at diagnosis was within the mid-50s, with 73% age <65 years and 27% age ≥65 years. In contrast, age ≥65 years emerged as the strongest predictor of poor survival, significant in both univariate (HR 5.3, 95% CI 1.7–18.2, p<9.00E-03) and multivariable analysis (HR 11.6, 95% CI 2.7–49.6, p<0.001). Treatment approaches, including surgery and radiation, did not confer a statistically significant survival benefit. Chemotherapy appeared to be associated with worse outcomes; however, this was based on only two patients, limiting interpretation. Overall, Kaplan–Meier curves underscored the lack of survival advantage from surgical intervention and highlighted the profound impact of age.
Conclusions: In this rare, highly malignant tumor patients, age is an important prognostic factor, with older patients experiencing significantly worse survival. Given the absence of clear survival benefit from surgical intervention, careful patient selection is warranted. In particular, older patients, who already demonstrate poor outcomes, may not be ideal candidates for aggressive surgical management. These findings emphasize the need for judicious treatment strategies and collaborative efforts to improve outcomes in this aggressive disease.
Figure 1: Overall survival.
Figure 2: Age-based survival.
Figure 3: Survival based on treatment modalities. GTR - gross total resection; Chemo - chemotherapy; Rad - radiation therapy; STR - subtotal resection.
Figure 4: Forest plot of multivariable analysis.
