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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).)

Meningiomas represent nearly one-third of all adult primary brain tumours. According to their clinical and histologic appearance, they can be divided into WHO grades I-III. Almost 90% of meningiomas are benign, showing favourable response to conventional therapies, however, patients diagnosed with grade 2 and 3 tumours may have a poor prognosis. In addition, high frequency of tumour recurrence renders treatments more challenging even in benign meningiomas. Molecular-pathological profiling of meningiomas could lead to development of more effective therapies. Although the cytogenetic background of these tumours are already well-characterised, the majority of related genes and mutations is still unknown. Recently, high-throughput techniques enabled better characterisation of mechanisms involved in meningioma development, progression and recurrence. Furthermore, epigenetic dysregulation could offer new opportunities for both diagnosis and treatment of meningiomas. We provide a comprehensive overview of cytogenetic and molecular genetic defects as well as epigenetic alterations in meningiomas. Many of these may serve as biomarker or therapeutic target in the near future.

Meningiomas are one of the most frequent intracranial tumours, with 13 histological types and three grades according to the 2007 WHO Classification of Tumours of the Central Nervous System. p53, as one of the most potent tumour suppressor proteins, plays a role in nearly 50% of human tumours. Poly(ADP-ribose) polymerase (PARP) is a DNA repair enzyme with high ATP demand. It plays a role in apoptosis by activating an apoptosis inducing factor, and in necrosis by consuming NAD+ and ATP. Only PARP1 has been investigated in detail in tumours out of the 17 members of the PARP superfamily; however, its role has not been studied in meningiomas yet. The aim of this study was to determine the role of p53 and PARP1 in meningiomas of different grade and to establish whether there is any correlation between the p53 and PARP1 expression. Both PARP1 and p53 have been expressed in all examined meningiomas. PARP1 labelled grade II tumours with a higher intensity as compared to grade I and III neoplasms, respectively. An increased p53 expression was noted in grade III meningiomas. There was no statistical correlation between p53 and PARP1 expression. Our data indicate that both PARP1 and p53 activation is a feature in meningiomas of higher grade, PARP1 overexpression being an early, whereas p53 overexpression, a late event in tumour progression.

Although tumour recurrence is an important and not infrequent event in meningiomas, predictive immunohistochemical markers have not been identified yet. The aim of this study was to address this clinically relevant problem by systematic retrospective analysis of surgically completely resected meningiomas with and without recurrence, including tumour samples from patients who underwent repeat surgeries. Three established immunohistochemical markers of routine pathological meningioma work-up have been assessed: the proliferative marker Ki-67 (clone Mib1), the tumour suppressor gene p53 and progesterone receptor (PR). All these proteins correlate with the tumour WHO grade, however the predictive value regarding recurrence and progression in tumour grade is unknown. One hundred and fourteen surgical specimens of 70 meningioma patients (16 male and 54 female) in a 16 years' interval have been studied. All tumours had apparently complete surgical removal. On Mib1, PR and p53 immunostained sections, the percentage of labelled tumour cells, the staining intensity and the multiplied values of these parameters (the histoscore) was calculated. Results were statistically correlated with tumour WHO grade, (sub)type, recurrence and progression in WHO grade at subsequent biopsies. Our results confirmed previous findings that the WHO grade is directly proportional to Mib1 and p53 and is inversely proportional to the PR immunostain. We have demonstrated that Mib1 and p53 have a significant correlation with and predictive value of relapse/recurrence irrespective of the histological subtype of the same WHO grade. As a quantitative marker, Mib1 has the best correlation with a percentage of labelled cells, whereas p53 with intensity and histoscore. In conclusion, the immunohistochemical panel of PR, p53, Mib1 in parallel with applying standard diagnostic criteria based on H&E stained sections is sufficient and reliable to predict meningioma recurrence in surgically completely resected tumours. [ABSTRACT FROM AUTHOR]