2638 - A Predictive Nomogram for Long-Term Outcomes of High-Grade Meningiomas Undergoing Postoperative Radiotherapy

T. Wu¹, L. Ren², J. Yu³, L. Hua², J. Deng³, and Y. Wang⁴; ¹Radiation Oncology Center, Huashan Hospital, Fudan University, Shanghai, Shanghai, China, ²Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China, ³Department of Neurosurgery of Huashan Hospital,Fudan University, Shanghai, Shanghai, China, ⁴Huashan Hospital, Fudan University, Shanghai, China

Purpose/Objective(s): Adjuvant radiotherapy after maximal surgical resection is recommended for grade 2 & 3 meningiomas. We are aimed to evaluate the efficacy of intensity-modulated radiation therapy (IMRT) after surgery in intracranial meningiomas last 10 years in our neurosurgical center. Materials/

Methods: We included 230 patients who were diagnosed as WHO grade 2 & 3 meningioma and underwent postoperative radiotherapy (prescription dose 54-60Gy) in our neurosurgical center from 2013 to 2023. Univariate and multivariate Cox regression analysis was used to analyze prognosis-related factors of these patients. A risk grouping nomogram was constructed to predict the progression risk of patients.
Results: 212 patients were diagnosed as grade 2 and 18 patients were diagnosed as grade 3 meningiomas. Subtotal resection was observed in 45 patients (19.6%). During the median follow-up of 30.91 months (1.7-136.5months), 35 patients recurred and 18 patients died of tumor progression. The progression-free survival (PFS) rates in the overall population at 3 ,5 and 8 years were 85.25%, 81.60% and 68.10%, respectively. The overall survival (OS) rates in the overall population at 3 ,5 and 8 years were 92.52%, 88.09% and 82.91%, respectively. We found that age older than 44, longer symptom duration, Ki-67 >8%, negative progesterone receptor (PR) expression, WHO grade 3, surgical and RT history (including SRS, SBRT, IMRT) were related with poor outcomes in high grade meningioma patients. Of note, older age, surgical and RT history were independent factors for poor prognosis. A nomogram with a C-index of 0.844 was constructed to predict the recurrence rates of high-grade meningioma patients.
Conclusion: Adjuvant radiotherapy after surgery is beneficial for high-grade meningioma patients. Notably, patients with older age, surgical and RT history derive less benefits from postoperative RT.