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Background: The risk of recurrence is overestimated by the Kaplan-Meier method when competing events, such as death without recurrence, are present. Such overestimation can be avoided by using the Aalen-Johansen method, which is a direct extension of Kaplan-Meier that accounts for competing events. Meningiomas commonly occur in older individuals and have slow-growing properties, thereby warranting competing risk analysis. The extent to which competing events are considered in meningioma literature is unknown, and the consequences of using incorrect methodologies in meningioma recurrence risk analysis have not been investigated., Methods: We surveyed articles indexed on PubMed since 2020 to assess the usage of competing risk analysis in recent meningioma literature. To compare recurrence risk estimates obtained through Kaplan-Meier and Aalen-Johansen methods, we applied our international database comprising ~ 8,000 patients with a primary meningioma collected from 42 institutions., Results: Of 513 articles, 169 were eligible for full-text screening. There were 6,537 eligible cases from our PERNS database. The discrepancy between the results obtained by Kaplan-Meier and Aalen-Johansen was negligible among low-grade lesions and younger individuals. The discrepancy increased substantially in the patient groups associated with higher rates of competing events (older patients with high-grade lesions)., Conclusion: The importance of considering competing events in recurrence risk analysis is poorly recognized as only 6% of the studies we surveyed employed Aalen-Johansen analyses. Consequently, most of the previous literature has overestimated the risk of recurrence. The overestimation was negligible for studies involving low-grade lesions in younger individuals; however, overestimation might have been substantial for studies on high-grade lesions., (© 2024. The Author(s).)

The purpose of this study was to evaluate spontaneous necrosis as a possible isolated factor for progression and recurrence in grade I meningiomas classified according to the current World Health Organization (WHO) classification. Meningiomas are the most frequently reported primary intracranial tumours, accounting for more than 35%. The 2016 WHO classification of central nervous system tumors stratifies meningiomas in grades I (benign), II (atypical), and III (malignant), according to histopathological aspects and the risk of progression or recurrence. Among 110 patients with intracranial meningiomas, 70 were WHO grade I meningiomas with no findings of atypia (G1WON), 15 were WHO grade I with necrosis (G1WN), 21 were WHO grade II (G2), and 4 were WHO grade III (G3). The mean follow-up was 5.9 ± 0.2 years. High performance scale (KPS ≥ 80) was different (p < 0.001) between WHO grade I meningiomas without (81.4%) and with (60%) necrosis. The 5-year mortality rate was 1.4, 6.7 and 5.9% for G1WON, G1WN and G2, respectively, with significant difference (p = 0.011) related to the presence of necrosis. The risk of recurrence was 3.7 times higher in G1WN than in G1WON (p = 0.017), and 4.2 times in G2 (p = 0.010). Progression-free survival (PFS) was clearly higher in patients with G1WON compared to G1WN and G2 (p = 0.002 and p < 0.001, respectively). There was no significant difference in PFS between G1WN and G2 (p = 0.692). Retreatment was also superior in meningioma with necrosis. Our findings provide clear statistical data to consider that patients with benign meningiomas and histologic findings of spontaneous necrosis are at increased risk of progression and recurrence compared to those with benign lesion without atypical features. Statistical analysis curves also suggest that these lesions behave more similarly to those currently classified as WHO grade II meningioma.