Stereotactic radiosurgery ensures an effective and safe long-term control of Koos grade IV vestibular schwannomas: a single-center, retrospective, cohort study

Risk analysis of radiosurgery for vestibular schwannoma: Systematic review and comparative study of 10-year outcomes

Background

Determine the benefit of stereotactic radiosurgery (SRS) compared to no treatment for sporadic vestibular schwannoma (VS) by calculating epidemiologic risk using 10-year data; apply the analysis to VS that have demonstrated linear growth.

Methods

PubMed, Google Scholar, Web of Science, and Cochrane Library are systematically reviewed for VS tumor control 10 years after SRS and compared to a historical cohort of untreated VS (primary risk analysis). Subgroups of VS limited by size and observed growth are compared to the untreated cohort (secondary analysis).

Results

Twenty-four studies of 4079 SRS-treated VS exhibited tumor control in 90.93% (87.0%-100%; SD 4.1%), while 1959 untreated VS exhibited control in 65.24%. SRS reduces the absolute risk (ARR) of tumor progression by 25.7% compared to no treatment. The number needed to treat (NNT) is 4 (3.892, 95% CI: 3.619-4.210). Subgroup analyses of (1) VS with definite linear growth before SRS result in a similar ARR of 29.4% and NNT 4 (3.395, 95% CI: 2.966-3.968), and (2) Koos 1 VS result in lower ARR 18.31% and higher NNT 6 (5.209; 95% CI: 4.018-7.401).

Conclusions

This "best-available" case-control study of 10-year data reveals that ARR and NNT are similar for VS with and without definite pretreatment linear growth. These comparisons may be applied to CPA diameters less than 2 cm. Results for Koos 1 tumors are different. This analysis quantifies the therapeutic benefit of SRS by comparative risk analysis. The level of evidence on this topic is low.

Management of treatment-naïve Koos grade IV vestibular schwannomas using hypofractionated Gamma Knife radiosurgery: a retrospective single-institution study

While single-fraction Gamma Knife radiosurgery (GKRS) has shown efficacy in managing vestibular schwannomas (VSs), some concerns have been raised regarding its safety profile, particularly in the context of hearing preservation. Hypofractionation has emerged as a promising approach to improving the safety profile. This retrospective, single-institution study evaluated patient outcomes following hypofractionated GKRS (hf-GKRS) for treatment-naïve Koos grade IV VSs. This study involved all patients with treatment-naïve Koos grade IV VSs who underwent hf-GKRS (3 or 5 fractions) between January 2018 and June 2021, with a follow-up period of ≥ 36 months. The outcomes assessed included local control (LC), the preservation of serviceable hearing as determined by the Gardner-Robertson hearing scale, and procedure-related adverse events. Twenty-nine patients (14 females, median age 49 years) were treated with three different dose regimens: 21 patients received 18 Gy in 3 fractions, 6 patients received 20 Gy in 5 fractions, and 2 patients received 25 Gy in 5 fractions. Prior to treatment, 13 patients (44.8%) had serviceable hearing, one (3.4%) presented with facial palsy, and four (13.8%) had trigeminal nerve dysfunction. The median tumor volume was 10.8 cm3. During a median radiological follow-up period of 60 months (range, 36-78 months), LC was achieved in all patients. All 13 patients retained serviceable hearing at the last follow-up. Trigeminal nerve dysfunction occurred in one patient (3.4%), while another patient (3.4%) needed a ventriculoperitoneal shunt insertion due to new-onset hydrocephalus. No new-onset facial palsy was observed. hf-GKRS shows promise as an effective and safe primary or adjuvant treatment for Koos grade IV VSs with non-life-threatening or debilitating symptoms. Future studies with larger cohorts and extended follow-up periods are needed to validate these findings and to refine fractionation schemes.

Central Neurocytoma Treated Using Supratentorial Ventricle Radiotherapy: A Single-Institution Analysis of Five Cases in Adjuvant or Salvage Settings After Surgery

INTRODUCTION

Central neurocytoma (CN) is an extremely rare tumor primarily located in the supratentorial ventricular system, categorized as a glioneuronal or neuronal tumor.

METHODS

This study presented a retrospective analysis of five CN patients who received adjuvant or salvage radiotherapy. Patients, aged 31-59 years, underwent radiation doses ranging from 60 Gy to 50.4 Gy over 27-30 fractions.

RESULTS

All patients achieved effective local tumor control without severe complications. The median follow-up period was 51.7 months, demonstrating 100% overall and progression-free survival rates.

DISCUSSION

Our study's clinical outcomes align with previous research, despite the limitation of a small sample size. Emphasizing the necessity for additional research, our findings added to the potential evidence of radiotherapy in managing CN. Larger, long-term studies were needed to confirm these promising results.

Stereotactic Radiosurgery for Vestibular Schwannoma With Radiographic Brainstem Compression

OBJECTIVE

The safety of single-treatment stereotactic radiosurgery (SRS) for vestibular schwannoma (VS) with radiographic evidence of brainstem compression but without motor deficit is controversial. Data on linear accelerator (linac)-based SRS in this setting are scarce. We address this with an outcomes report from an unselected series of patients with VS with radiographic brainstem compression treated with linac SRS.

METHODS

We included 139 patients with unilateral VS (any size) with radiographic brainstem compression (all without serious brainstem neurological deficits). The SRS prescription dose was 12.5 Gy (single fraction) using 6MV linac-produced photon beams, delivered with a multiple arc technique. Inclusion criteria required at least 1 year of radiographic follow-up with magnetic resonance imaging. The primary endpoint was freedom from serious brainstem toxicity (≥grade 3 Common Terminology Criteria for Adverse Events v5); the secondary was freedom from enlargement (tumor progression or any requiring intervention). We assessed serious cranial nerve complications, excluding hearing loss, defined as Common Terminology Criteria for Adverse Events v5 grade 3 toxicity.

RESULTS

Median magnetic resonance imaging follow-up time was 5 years, and median tumor size was 2.5 cm in greatest axial dimension and 5 ml in volume. The median brainstem D0.03 ml=12.6 Gy and median brainstem V10 Gy=0.4 ml. At 5 years, the actuarial freedom from serious brainstem toxicity was 100%, and freedom from tumor enlargement (requiring surgery and/or due to progression) was 90%. Severe facial nerve damage in patients without tumor enlargement was 0.9%.

CONCLUSION

Linac-based SRS, as delivered in our series for VS with radiographic brainstem compression, is safe and effective.

Wait-and-scan management in sporadic Koos grade 4 vestibular schwannomas: A longitudinal volumetric study

Background

Volumetric natural history studies specifically on large vestibular schwannomas (VSs), commonly classified as Koos grade 4, are lacking. The aim of the current study is to present the volumetric tumor evolution in sporadic Koos grade 4 VSs and possible predictors for tumor growth.

Methods

Volumetric tumor measurements and tumor evolution patterns from serial MRI studies were analyzed from selected consecutive patients with Koos grade 4 VS undergoing initial wait-and-scan management between January 2001 and July 2020. The significant volumetric threshold was defined as a change in volume of ≥10%.

Results

Among 215 tumors with a median size (IQR) of 2.7 cm3 (1.8-4.2), 147 tumors (68%) demonstrated growth and 75 tumors (35%) demonstrated shrinkage during follow-up. Growth-free survival rates (95% CI) at 1, 2, 5, and 10 years were 55% (48-61), 36% (29-42), 29% (23-36), and 28% (21-34), respectively and did not significantly differ in tumors> 20 mm (Chi-square = .40; P-value = .53). Four tumor evolution patterns (% of total) were observed: continued growth (60); initial growth then shrinkage (7); continued shrinkage (27); and stability (5). Good hearing (adjusted HR 2.21, 95% CI 1.48-3.30; P < .001) and peritumoral edema (adjusted HR 2.22, 95% CI 1.18-4.13; P = .01) at diagnosis were significantly associated with an increased likelihood of growth.

Conclusions

Koos grade 4 VSs show a wide variety in size and growth. Due to variable growth patterns, an initial wait-and-scan strategy with short scan intervals may be an acceptable option in selected tumors, if no significant clinical symptoms of mass effect that warrant treatment are present.

Single-fraction radiosurgery outcomes for large vestibular schwannomas in the upfront or post-surgical setting: a systematic review and International Stereotactic Radiosurgery Society (ISRS) Practice Guidelines

PURPOSE

To perform a systematic review of literature specific to single-fraction stereotactic radiosurgery (SRS) for large vestibular schwannomas (VS), maximum diameter ≥ 2.5 cm and/or classified as Koos Grade IV, and to present consensus recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS).

METHODS

The Medline and Embase databases were used to apply the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach. We considered eligible prospective and retrospective studies, written in the English language, reporting treatment outcomes for large VS; SRS for large post-operative tumors were analyzed in aggregate and separately.

RESULTS

19 of the 229 studies initially identified met the final inclusion criteria. Overall crude rate of tumor control was 89% (93.7% with no prior surgery vs 87.7% with prior surgery). Rates of salvage microsurgical resection, need for shunt, and additional SRS in all series versus those with no prior surgery were 9.6% vs 3.3%, 4.7% vs 6.4% and 1% vs 0.9%, respectively. Rates of facial palsy and hearing preservation in all series versus those with no prior surgery were 1.3% vs 3.4% and 34.2% vs 40.4%, respectively.

CONCLUSIONS

Upfront SRS resulted in high rates of tumor control with acceptable rates of facial palsy and hearing preservation as compared to the results in those series including patients with prior surgery (level C evidence). Therefore, although large VS are considered classic indication for microsurgical resection, upfront SRS can be considered in selected patients and we recommend a prescribed marginal dose from 11 to 13 Gy (level C evidence).