McBain, Catherine

Importance In the literature, there is a lack of data reporting tumor control rates after radiotherapy in actively growing vestibular schwannomas (VS). Data for this rarely studied population are needed. Objective To estimate tumor control rates in radiologically growing VS treated with first-line radiotherapy. Design, Setting, and Participants This international, multicenter cohort study used prospectively collected data from patients with growing unilateral VS treated first-line with radiotherapy between January 2000 and December 2023 from 8 tertiary referral skull base units. The data were analyzed in June 2025. Exposures Radiotherapy as an initial treatment for VS. Main Outcomes and Measures The primary outcome was treatment failure, ie VS growth postradiotherapy, which was predefined as an increase in maximum intracranial tumor diameter (ICTD) of 3 mm or greater within the first 2 years after radiotherapy or 2 mm or greater thereafter. Secondary outcomes were treatment failure based on different definitions of VS growth: (1) an increase in ICTD of 2 mm or greater, (2) an increase in ICTD of 3 mm or greater, and (3) conversion to surgery. Results A total of 1883 patients (975 female individuals [51.8%]; median age at diagnosis, 63 years [IQR, 53-71 years]) were included in the study. Using the primary definition of treatment failure (an increase in ICTD of ≥3 mm within the first 2 years postradiotherapy or ≥2 mm thereafter), the Kaplan-Meier estimate yielded a 10-year tumor control rate of 76.1% (95% CI, 72.7%-79.2%). For secondary outcome definitions, 10-year tumor control rates were 60.1% (95% CI, 57.5%-64.3%) for an ICTD increase of 2 mm or greater, 78.3% (95% CI, 75.0%-81.2%) for an increase of 3 mm or greater, and 92.6% (95% CI, 90.4%-94.3%) for conversion to surgery. Neither pretreatment tumor size nor tumor location (intracanalicular vs extracanalicular) were significantly associated with treatment failure. Conclusions and Relevance The results of this cohort study provide tumor control outcomes for radiologically growing VS treated with radiotherapy using several clinically relevant definitions of growth. By focusing exclusively on this rarely isolated subgroup, the findings offer targeted data to potentially inform treatment expectations and future research.

Abstract Purpose: In a post hoc analysis of the CATNON trial (NCT00626990), we explored whether adding temozolomide to radiotherapy improves outcome in patients with IDH1/2 wildtype (wt) anaplastic astrocytomas with molecular features of glioblastoma [redesignated as glioblastoma, isocitrate dehydrogenase–wildtype (IDH-wt) in the 2021 World Health Organization (WHO) classification of central nervous system tumors]. Patients and Methods: From the randomized phase III CATNON study examining the addition of adjuvant and concurrent temozolomide to radiotherapy in anaplastic astrocytomas, we selected a subgroup of IDH1/2wt and H3F3Awt tumors with presence of TERT promoter mutations and/or EGFR amplifications and/or combined gain of chromosome 7 and loss of chromosome 10. Molecular abnormalities including MGMT promoter methylation status were determined by next-generation sequencing, DNA methylation profiling, and SNaPshot analysis. Results: Of the 751 patients entered in the CATNON study, 670 had fully molecularly characterized tumors. A total of 159 of these tumors met the WHO 2021 molecular criteria for glioblastoma, IDH-wt. Of these patients, 47 received radiotherapy only and 112 received a combination of radiotherapy and temozolomide. There was no added effect of temozolomide on either overall survival [HR, 1.19; 95% confidence interval (CI), 0.82–1.71] or progression-free survival (HR, 0.87; 95% CI, 0.61–1.24). MGMT promoter methylation was prognostic for overall survival, but was not predictive for outcome to temozolomide treatment either with respect to overall survival or progression-free survival. Conclusions: In this cohort of patients with glioblastoma, IDH-wt temozolomide treatment did not add benefit beyond that observed from radiotherapy, regardless of MGMT promoter status. These findings require a new well-powered prospective clinical study to explore the efficacy of temozolomide treatment in this patient population.

Abstract Background Survival in patients with IDH1/2-mutant (mt) anaplastic astrocytomas is highly variable. We have used the prospective phase 3 CATNON trial to identify molecular factors related to outcome in IDH1/2mt anaplastic astrocytoma patients. Methods The CATNON trial randomized 751 adult patients with newly diagnosed 1p/19q non-codeleted anaplastic glioma to 59.4 Gy radiotherapy +/− concurrent and/or adjuvant temozolomide. The presence of necrosis and/or microvascular proliferation was scored at central pathology review. Infinium MethylationEPIC BeadChip arrays were used for genome-wide DNA methylation analysis and the determination of copy number variations (CNV). Two DNA methylation-based tumor classifiers were used for risk stratification. Next-generation sequencing (NGS) was performed using 1 of the 2 glioma-tailored NGS panels. The primary endpoint was overall survival measured from the date of randomization. Results Full analysis (genome-wide DNA methylation and NGS) was successfully performed on 654 tumors. Of these, 432 tumors were IDH1/2mt anaplastic astrocytomas. Both epigenetic classifiers identified poor prognosis patients that partially overlapped. A predictive prognostic Cox proportional hazard model identified that independent prognostic factors for IDH1/2mt anaplastic astrocytoma patients included; age, mini-mental state examination score, treatment with concurrent and/or adjuvant temozolomide, the epigenetic classifiers, PDGFRA amplification, CDKN2A/B homozygous deletion, PI3K mutations, and total CNV load. Independent recursive partitioning analysis highlights the importance of these factors for patient prognostication. Conclusion Both clinical and molecular factors identify IDH1/2mt anaplastic astrocytoma patients with worse outcome. These results will further refine the current WHO criteria for glioma classification.