Analysis of radiotherapy in patients with intermediate- and high-risk meningiomas.

Purpose: This study aimed to investigate treatment outcomes in patients with intermediate- and high-risk meningioma who underwent radiotherapy (RT) and identify prognostic factors for progression-free survival (PFS). In addition, failure patterns after RT were analyzed.

Materials and methods: We retrospectively reviewed 61 patients with intermediate- and high-risk meningiomas, categorized according to the NRG Oncology/Radiation Therapy Oncology Group 0539 trial, who underwent surgery followed by adjuvant or salvage RT.

Results: We included 12 and 49 patients with intermediate- and high-risk meningiomas, respectively. A total of 26 cases of tumor progression and 17 deaths after RT were identified. The 5-year PFS and overall survival of the entire cohort were 55.8% and 74.2%; intermediate-risk group, 80.2% and 100%; high-risk group, 48.7% and 67.1%, respectively. The World Health Organization (WHO) grade 3 (hazard ratio [HR], 16.7; 95% confidence interval [CI], 3.0 to 92.3; p = 0.001) and recurrent tumor (HR, 41.2; 95% CI, 3.6 to 473.6; p = 0.003) were identified as adverse prognostic factors for PFS in high-risk patients. Among the 15 patients who had recurrence after conventional fractionated radiotherapy (CFRT), 13 experienced local failure (LF) and two experienced distant failure.

Conclusion: RT with adjuvant or salvage intent showed favorable treatment outcomes in patients with intermediate- to high-risk meningioma. WHO grade 3 histology and recurrent tumors were identified as adverse prognostic factors for PFS in high-risk patients. LF was the dominant failure pattern after CFRT, accounting for 86.7% of all recurrences. These findings underscore the need for further studies on dose-escalated RT to enhance local control in patients with these adverse features.