Long-term volumetric analysis of vestibular schwannomas following stereotactic radiotherapy: Practical implications for follow-up

Clinical and Translational Radiation Oncology

M. Regnier¹  M. Wanet²  O. Fouard³  J.F. Daisne⁴  T. Gustin⁴ 

[1] Department of Oncology and Leuven Cancer Institute, Katholieke Universiteit Leuven, Leuven, Belgium;Radiation Oncology Department, University Hospitals Leuven, Katholieke Universiteit Leuven, Leuven, Belgium;Neurosurgery Department, CHU UCL Namur site Godinne, Université Catholique de Louvain, Yvoir, Belgium;Radiation Oncology Department, CHU UCL Namur Site Sainte-Elisabeth, Université Catholique de Louvain, Namur, Belgium;

关键词: Vestibular schwannoma;    Stereotactic radiotherapy;    Volumetry;    Pseudoprogression;    Long-term follow-up;   

DOI  :  

来源: DOAJ

【 摘 要 】

Background and purpose: Transient tumor swelling is a well-known phenomenon following radiotherapy for vestibular schwannomas (VS). We analyzed the long-term volumetric changes of VS after LINAC radiosurgery, in order to determine a time interval during which a true tumor progression can be distinguished from a pseudoprogression. Methods: Among 63 patients with VS treated by one fraction or fractionated radiotherapy, we selected 52 of them who had a minimal follow-up of 5 years. Maximal axial diameter and three-dimensional tumor volume were measured on each MRI scan. Volume changes were interpreted using different error margins ranging from 10 to 20%. Patients were categorized according to the tumor evolution pattern over time. Results: Median follow-up was 83 months. One tumor (1.9%) remained stable and 26.9% had continuous shrinkage. Applying an error margin of 13%, a transient tumor enlargement was observed in 63.5% of patients, with a first peak at 6–12 months and a late peak at 3–4 years. A true progression was suspected in 4 (7.7%) patients, tumor regrowth starting after the 3rd or 4th year post-treatment. Only one patient required salvage radiotherapy. Conclusion: Transient swelling of VS following radiotherapy is generally an early phenomenon but may occur late. In the first 5 years, a true tumor progression cannot be differentiated from a pseudoprogression. A significant tumor expansion observed on 3 sequential MRI scans after the 3rd year may be suggestive of treatment failure. Long-term follow-up is therefore mandatory and no decision of salvage treatment should be made until the 6th year.

【 授权许可】

Unknown