Single Institutional Experience With Observing 564 Vestibular Schwannomas

Abstract

Objective To characterize the risk and predictors of growth during observation of vestibular schwannomas (VS). Study Design Retrospective case series. Setting Single academic, tertiary care center. Patients 564 consecutive VS patients who underwent at least two MRI studies prior to intervention. Intervention(s) Serial MRI studies Main outcome measure(s) Tumor growth, defined as a ≥2 mm increase in the maximum tumor diameter between consecutive MRI studies, or between the first and last study. Results A total of 1,296 patients (1995–2015) with VS were identified. Of those, 564 patients (median age 59.2 years; 53.5% female) were initially observed and underwent multiple MRI studies (median follow-up 22.9 months, interquartile range [IQR] 11.7 – 42.7). The median maximum tumor diameter at presentation was 1.00 cm (IQR 0.6 – 1.51 cm). In all, 40.8% of tumors demonstrated growth and 32.1% underwent intervention (21.5% microsurgery, 10.5% radiation) during the surveillance period. Multivariable Cox regression analysis showed that for each tumor, the risk of growth or intervention was significantly increased for larger initial VS diameters (HR=2.22; 95% CI: 1.90 – 2.61) and when disequilibrium was a presenting symptom (HR=1.70; 95% CI: 1.30 – 2.23). Patient age, gender, aspirin use and presenting symptoms of asymmetric hearing loss, tinnitus, and vertigo, were not associated with tumor growth. Conclusions To date, this is the largest series of observed VS reported in the literature. Risk of VS growth is significantly increased among patients who present with larger tumors and who have concomitant disequilibrium. IRB 151481 Define Professional Practice Gap & Educational Need No cohort with this sample size has assessed vestibular schwannoma growth rates in conjunction with this number of variables. Learning Objective To characterize vestibular schwannoma growth rates and predictors of growth.

Aspirin does not prevent growth of vestibular schwannomas: A case‐control study

“…Our results do not show an association between aspirin intake and VS stability. This is in contrast to previously reported evidence of efficacy of aspirin in vitro as well as supporting observational data, but agree with those of one other similar large retrospective study . We demonstrated that the majority of patients would be able to take regular aspirin if found to be effective, with less than 10% being unable due to contraindications or high risk of gastrointestinal bleeding.…”

“…These findings are in contrast to the previously reported evidence suggesting a potential mechanism and efficacy from in vitro studies, as well as a previously reported observational study . However, the results agree with one other similar large retrospective study by Hunter et al, which found that larger tumor size and disequilibrium at presentation were the only factors predictive of growth and not aspirin or other nonsteroidal anti‐inflammatory drug (NSAID) use …”

“…The present study used a minimum criterion for growth of 2 mm, selected to reduce the well‐documented risk of measurement error when using linear measurements . This is identical to the previous studies by Hunter et al; however, the previous 2014 Kandathil study used two alternative definitions of growth. The first was a categorical outcome of growth versus no growth, but with no criteria for a minimum change in size.…”

“…Interestingly, if the present study's participants are grouped into aspirin users and nonusers, there is very little difference in the mean tumor size between groups (11.36 mm vs. 11.34 mm). The study by Hunter et al examining factors predictive of VS growth demonstrated a greater than doubling of risk of growth with each centimeter increase in tumor size . A similar previous study suggested an increased risk of growth of 14% with each millimeter in increase of tumor size .…”

“…18,19 However, the results agree with one other similar large retrospective study by Hunter et al, which found that larger tumor size and disequilibrium at presentation were the only factors predictive of growth and not aspirin or other nonsteroidal anti-inflammatory drug (NSAID) use. 23,24 This is disappointing given that aspirin is a relatively safe, inexpensive, and a generally well-tolerated oral medication that could have been a popular option to prevent growth of VS if found to be effective.…”