Review of Atypical and Anaplastic Meningiomas: Classification, Molecular Biology, and Management

Abstract

Although the majority of meningiomas are slow-growing and benign, atypical and anaplastic meningiomas behave aggressively with a penchant for recurrence. Standard of care includes surgical resection followed by adjuvant radiation in anaplastic and partially resected atypical meningiomas; however, the role of adjuvant radiation for incompletely resected atypical meningiomas remains debated. Despite maximum treatment, atypical, and anaplastic meningiomas have a strong proclivity for recurrence. Accumulating mutations over time, recurrent tumors behave more aggressively and often become refractory or no longer amenable to further surgical resection or radiation. Chemotherapy and other medical therapies are available as salvage treatment once standard options are exhausted; however, efficacy of these agents remains limited. This review discusses the risk factors, classification, and molecular biology of meningiomas as well as the current management strategies, novel therapeutic approaches, and future directions for managing atypical and anaplastic meningiomas.

Meningioma: A Review of Epidemiology, Pathology, Diagnosis, Treatment, and Future Directions

“…Most agree that there is no role for RT for WHO grade I tumors, unless in the setting of unresectable symptomatic initial or recurrent tumors. While the role of radiotherapy in WHO grade II GTR tumors not fully elucidated, multiple phase II and randomized controlled trials are trying to shed light on this issue [ 116 ]. A phase II trial (RTOG 0539) demonstrated that their intermediate risk group (newly diagnosed WHO grade II GTR (69.2%) and recurrent WHO grade I with any resection extent (30.8%)), when treated with RT (standard dose of 54 Gy), had a 98.3% 3-year progression-free survival (PFS) and 96% 3-year overall survival (OS) ( Table 6 ) [ 117 ].…”

Brain Invasion in Meningioma—A Prognostic Potential Worth Exploring

“…There are no other established therapy options and especially, more aggressive meningiomas are challenging to treat. After multiple rounds of resection and radiation there is no established treatment alternative to oppose further disease progression, while individualized treatment approaches are frequently offered [8].…”

A Clinical Prognostic Model Based on Preoperative Hematological and Clinical Parameters Predicts the Progression of Primary WHO Grade II Meningioma

“…The WHO classification is an important prognostic tool that is based on histological criteria, but cannot fully predict tumor progression. There is substantial variation within the same grade among tumors, with studies reporting indolent behavior with no progression in up to 71% of AM cases ( 3 ). Therefore, it is especially important to accurately predict tumor progression and realize hierarchical tumor management.…”

“…Considering the efficacy and neurotoxicity of radiotherapy, it is still controversial as to whether PORT is necessary as a routine treatment for AM. Based on the existing evidence, PORT is recommended for AM with STR, especially for skull base meningiomas ( 3 , 50 ). However, the role of PORT in patients with completely resected AM remains undefined, and there is still no unified consensus on whether these patients need radiotherapy, or the dose of radiotherapy ( 17 ).…”

“…AM is regarded as the transition stage between grade I/benign and grade III/malignant. Currently, surgical resection is regarded as the first-line treatment for AM, but the 5-year progression rate can reach 29–58% ( 3 ), and the progression-free survival (PFS) varies greatly among patients with AM. In recent decades, neurosurgeons have attempted to identify appropriate prognostic factors to classify the progression risk of patients with AM and to design subsequent treatment and follow-up protocols.…”