Atypical meningioma outcome
In atypical meningiomas bone involvement and large meningioma peritumoral edema are associated with increased tumor progression.
Recurrence
see Atypical Meningiomas: Histological and Clinical Factors Associated With Recurrence 1).
Grade II atypical meningiomas tend to recur and grow faster.
Retrospective series supports the observation that postoperative radiotherapy likely results in lower recurrence rates of gross totally resected atypical meningiomas.
Patients older than 55 years and those with mitosis noted during pathological examination had a significant risk of recurrence after GTR; for these patients, postoperative radiotherapy is recommended 2).
After GTR without postoperative radiation, AMs have a high recurrence rate. Most recurrences occurred within 5 years after resection. Recurrences caused numerous reoperations per patient and shortened survival 3).
A multicenter prospective trial will ultimately be needed to fully define the role of radiotherapy in managing gross totally resected atypical meningiomas 4).
Study limitations, including inadequate statistical power, may underlie the studies' inability to demonstrate a statistically significant benefit for adjuvant radiotherapy in AM. Because these tumors preferentially recur within 5 years of surgical resection, future studies should define whether early adjuvant therapy should become part of the standard treatment paradigm for completely excised tumors 5).
Brain invasion and high mitotic rates may predict recurrence. After gross total resection (GTR) of AMs, EBRT appears not to affect progression free survival and overall survival, suggesting that observation rather than EBRT may be indicated after GTR 6).
Outcome
The rarity and the inconsistent criteria for defining atypical meningioma prior to the WHO 2007 classification made its management and prognostic factors poorly understood. Only few articles have addressed the survival rates of WHO-classified atypical meningiomas. The small number or the disproportionate representation of irradiated patients was a weakness for these articles.
The most important prognostic factor in determining recurrence was Simpson grading. There was no statistically significant impact of adjuvant radiotherapy on the recurrence of atypical meningiomas. Metaanalysis for the existing literature is needed 7).