Dataset Information

Comparing the impact of upfront radiosurgery versus expectation in vestibular schwannoma (the V-REX study): protocol for a randomised, observer-blinded, 4-year, parallel-group, single-centre, superiority study.

ABSTRACT:

Introduction

The optimal management of small-sized to medium-sized vestibular schwannoma (VS) is a matter of controversy. Clinical results of the prevailing treatment modalities (microsurgery, stereotactic radiosurgery (SRS), and conservative management (CM)) are documented, but comparative studies are few, and none are randomised or blinded. Upfront radiosurgery, or a careful follow-up by MRI with subsequent treatment on growth, are two strategies used at many centres. The present study aims at comparing these strategies by randomising individuals with newly diagnosed tumours to either upfront SRS or initial CM.

Methods and analysis

The Vestibular Schwannoma: Radiosurgery or Expectation study is designed as a randomised, controlled, observer-blinded, single-centre superiority trial with two parallel groups. Eligible patients will be randomised using sequentially numbered opaque sealed envelopes, and the radiosurgery group will undergo standard Gamma Knife Radiosurgery (GKRS) within 2 months following randomisation. The primary endpoint is tumour growth measured as volume ratio V_4years/V_baseline and volume doubling time, evaluated by annual T1 contrast MRI volumetric analysis. Secondary endpoints include symptom and sign development measured by clinical examination, audiovestibular tests, and by patient's responses to standardised validated questionnaires. In addition, the patient's working status, and the health economics involved with both strategies will be evaluated and compared. All outcome assessments will be performed by blinded observers. Power analysis indicates that 100 patients is sufficient to demonstrate the effect of GKRS on tumour volume.

Ethics and dissemination

The trial has ethical approval from the Regional Ethical Committee (23503) and funding from The Western Norway Regional Health Authority. Trial methods and results will be reported according to the Consolidated Standards of Reporting Trials 2010 guidelines in a peer-reviewed journal.

Trial registration number

Clinical trials: NCT02249572. Haukeland University Hospital record: 2014/314. Regional Ethical Committee (REC West): 23 503. The Western Norway Regional Health Authority: 912 281.

SUBMITTER: Dhayalan D

PROVIDER: S-EPMC7978102 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe management of vestibular schwannoma has evolved over the past hundred years. In the last decades, surgery has been gradually replaced by radiation therapy as a primary treatment modality, particularly for small tumors, due to the less invasive nature and the compared reported outcomes in tumor control and hearing preservation. However, irradiation sometimes fails to stop tumor growth. In a long-term follow-up after primary fractionated stereotactic radiotherapy, the rate of treatment failure was reported as 3% and needed surgical salvage. For single-fraction modality, Hasegawa et al. reported salvage treatment after primary Gamma Knife radiosurgery in 8%, where 90% of these underwent surgery and 50% of those who were treated with a second gamma knife surgery required surgical intervention later. An increase in tumor volume by more than 10-20%, tumor growth after three years, and no return to pretreatment volume after transient swelling have been considered as tumor recurrence rather than pseudoprogression, a transient increase in tumor volume after radiotherapy that occurs up to 30% of cases. It has been reported that microsurgery after radiotherapy is more difficult, with most authors reporting a loss of defined arachnoid planes and worse cranial nerve outcomes, especially for hearing and facial nerve function.Case descriptionA 43-year-old female patient was incidentally (asymptomatic) diagnosed on a magnetic resonance imaging (MRI) scan harboring a left vestibular schwannoma, grade T2 (Hannover classification), in 2015. Neurologic examination was unremarkable, and audiometry testing was normal. She was initially treated with observation. Three years later, in 2018, the lesion had enlarged, becoming a grade T3a and reaching the cistern of the cerebellopontine angle. The tumor was then treated with fractionated stereotactic radiosurgery (5 sessions of 5 Gy). MRI scans in 2019 and 2020 showed slight tumor growth. This enlargement was attributed to a pseudoprogression after radiosurgery, and only observation was advocated. In 2022, 4 years later, after radiosurgery, the tumor was still growing, and the patient began to suffer from hearing loss. A failure treatment was considered, and microsurgery was indicated. The patient was counseled about the risk of functional nerve impairment, and surgical consent was obtained. A retro sigmoid approach was planned. A gross total resection was attempted due to the clear subperineural plane during tumor dissection and because it was the only option that would provide a cure for the patient. The adjacent neurovascular structures were firmly adhered to the tumor capsule, which represented a major challenge for microdissection. The tumor was soft, without significant bleeding. A total resection was achieved, and the facial nerve was anatomically preserved. The patient developed facial paresis (House-Brackmann III) in the immediate postoperative period, which improved at the 6-month follow-up. Hearing loss did not improve. Postoperative MRI showed total resection.ConclusionMicrosurgery after radiotherapy for vestibular schwannoma is challenging in terms of indication, when to indicate, resection target, difficulty in dissection due to local changes, and outcome. Gross total resection may be considered, as it is the only treatment that may provide a cure for the patient. However, the patient should be counseled about the risks.

Project description:ObjectiveRepeated controlled studies have revealed that stereotactic radiosurgery is better than microsurgery for patients with vestibular schwannoma (VS) <3 cm in need of intervention. In this systematic review we aimed to compare results from single-fraction stereotactic radiosurgery (SRS) to fractionated stereotactic radiotherapy (FSRT) for patients with VS.Data sources and eligibility criteriaWe systematically searched MEDLINE, Web of Science, Embase and Cochrane and screened relevant articles for references. Publications from 1995 through 2014 with a minimum of 50 adult (>18 years) patients with unilateral VS, followed for a median of >5 years, were eligible for inclusion. After screening titles and abstracts of the 1094 identified articles and systematically reviewing 98 of these articles, 19 were included.InterventionPatients with unilateral VS treated with radiosurgery were compared to patients treated with fractionated stereotactic radiotherapy.ResultsNo randomized controlled trial (RCT) was identified. None of the identified controlled studies comparing SRS with FSRT were eligible according to the inclusion criteria. Nineteen case series on SRS (n = 17) and FSRT (n = 2) were included in the systematic review. Loss of tumor control necessitating a new VS-targeted intervention was found in an average of 5.0% of the patients treated with SRS and in 4.8% treated with FSRT. Mean deterioration ratio for patients with serviceable hearing before treatment was 49% for SRS and 45% for FSRT, respectively. The risk for facial nerve deterioration was 3.6% for SRS and 11.2% for FSRT and for trigeminal nerve deterioration 6.0% for SRS and 8.4% for FSRT. Since these results were obtained from case series, a regular meta-analysis was not attempted.ConclusionSRS and FSRT are both noninvasive treatment alternatives for patients with VS with low rates of treatment failure in need of rescue therapy. In this selection of patients, the progression-free survival rates were on the order of 92-100% for both treatment options. There is a lack of high-quality studies comparing radiation therapy alternatives for patients with VS. Finally, 19 articles reported long-term tumor control after SRS, while only 2 articles reported long-term FSRT results, making effect estimates more uncertain for FSRT.