TOPLINE:

Radiotherapy was effective in controlling growing vestibular schwannomas over 10 years, regardless of pretreatment tumor size or location.

METHODOLOGY:

• Vestibular schwannomas (acoustic neuromas) are benign nerve sheath tumors that have unpredictable growth and can cause symptoms such as hearing loss, tinnitus, and loss of balance. Radiotherapy is an established treatment for small to medium tumors, with reported control rates exceeding 95%. However, those figures come from small, single-center studies, often including patients with stable, rather than radiologically growing, tumors.
• Researchers conducted an international, multicenter cohort study using prospectively collected data from 1883 patients with growing unilateral vestibular schwannomas who received first-line radiotherapy between 2000 and 2023. Median age at diagnosis was 63 years.
• The primary outcome was treatment failure, defined as an increase in maximum intracranial tumor diameter of ≥ 3 mm within the first 2 years or at least 2 mm thereafter. Secondary outcomes evaluated treatment failure using three different definitions: a postradiotherapy increase in intracranial tumor diameter of ≥ 2 mm, increase of at least 3 mm, and conversion to surgery.
• The median tumor size before radiotherapy was 14 mm and 86.9% of schwannomas were extracanalicular. The median follow-up duration was 3.6 years.

TAKEAWAY:

• Using the primary definition of treatment failure, the 10-year tumor control rate was 76.1%. That outcome varied according to the secondary definitions, with 10-year control rates of 60.1% for at least 2 mm growth, 78.3% for ≥ 3 mm growth, and 92.6% for conversion to surgery.
• After adjusting for clustering by treatment centers, neither pretreatment tumor size (hazard ratio [HR], 0.99; P = .35) nor intracanalicular vs extracanalicular tumor location (HR, 1.04; P = .85) were associated with treatment failure.
• The findings indicate that vestibular schwannomas that do enlarge by ≥ 3 mm usually do so within 2 years of radiotherapy, the authors noted. Of tumors that showed such early growth, only 6.6% showed further progression beyond 3 years.

IN PRACTICE:

Compared with previous, small studies, these results offer “a more precise assessment of radiotherapy efficacy” for this rarely studied patient population, the authors wrote. “These findings may inform clinical decision-making, improve patient counselling, and help bridge existing knowledge gaps regarding the treatment of actively growing [vestibular schwannomas] with radiotherapy,” they concluded.

SOURCE:

This study was led by Daniele Borsetto, MPhil, Cambridge University Hospitals, Cambridge, England, and was published online in JAMA Otolaryngology-Head & Neck Surgery.

LIMITATIONS:

Limitations included limited certainty of long-term outcomes due to median follow-up of 3.6 years, lack of volumetric tumor analysis, and substantial heterogeneity in the radiotherapy modalities across centers.

DISCLOSURES:

The authors did not report any funding information. One author disclosed receiving grants from Regeneron, Cochlear, Advanced Bionics, and Medel outside this work. No other disclosures were reported.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.