EARLY VOLUMETRIC VARIATIONS IN INTRACRANIAL MENINGIOMA AFTER LINEAR ACCELERATOR-BASED RADIATION THERAPY

Objective: This study aimed to evaluate the risk factors for early meningioma volume expansion after linear accelerator (LINAC)-based radiation treatment. Methods: All reference and tumor volumes were measured using a semiautomated 3D slicer. We estimated the volume percent change based on the baseline volume at every follow-up point. The area under the receiver operating characteristic curve was used to determine optimal cut-off values of the initial tumor volumes and biologically effective dose for predicting tumor-volume increase. Results: A total of 32 meningiomas were detected in 28 patients who underwent LINAC-based radiation treatment for the first time from July 7, 2014, in our hospital. We observed an increase in tumor volume during the short-term follow-up in groups with higher initial tumor volume, higher biologically effective dose, and older age (log rank test; p = 0.018, p = 0.021, and p = 0.004, respectively). In addition, tumor-volume increase was significantly associated with peritumoral edema development. Conclusions: We believe there may be a correlation between early tumorvolume increase and peritumoral edema development post-radiation. Therefore, precautions should be taken when treating patients with early tumor volume increase that exceeds 15%, especially in old age, with high initial tumor volume, and high prescription dosages.