Anaplastic Meningioma: Clinical Characteristics, Prognostic Factors and Survival Outcome

Abstract

Background: Anaplastic meningioma is very rare and is generally known to have a poor prognosis. However, due to its rarity, the relationship between clinical prognosis and prognostic factors is not clear. We analyzed the prognostic factors influencing survival outcomes of patients with anaplastic meningioma. Moreover, we analyzed on the progression pattern and the response to treatment about anaplastic meningioma.

Methods: Retrospective review of 48 patients with diagnosis of World Health Organization (WHO) grade 3 meningioma was performed. According to diagnosis type, primary anaplastic meningioma was included in 28 cases and secondary anaplastic meningioma in 20 cases. Gross total resection was performed in 36 patients (75.0%), and 32 patients (66.7%) received adjuvant radiotherapy after tumor resection with confirmed WHO grade 3 meningioma. Kaplan-Meier survival curve and Cox proportional hazards modeling were used for outcome analysis.

Results: The median progression-free survival (PFS) and overall survival (OS) were 13.9 months (95% confidence interval [CI], 8.8 to 19.1) and 56.9 months (95% CI, 24.1 to 89.7), respectively. Adjuvant radiotherapy was a robust prognostic factor for PFS and OS. Extent of resection and diagnosis type which appeared to be significant prognostic factors in univariate analysis were failed to prove statistical significance in multivariate analysis.

Conclusion: Adjuvant radiotherapy is an essential treatment arm in patients with anaplastic meningiomas. Stereotactic radiosurgery seems to play an important role as a salvage treatment. But chemotherapy seems to have limited efficacy. Because of the disseminated nature of the disease, further investigations to improve survival outcome are needed.

Keywords: Adjuvant radiotherapy; Anaplastic meningioma; Prognosis; Progression; Surgery.

Fig. 1. Kaplan–Meier survival analysis. A and B: The 2-year and 5-year progression-free survival (PFS) rate 40.0% and 21.8%, respectively (A). The 2-year and 5-year overall survival (OS) rate 76.7% and 47.9%, respectively (B). C and D: Adjuvant radiotherapy showed statistically meaningful result in both PFS (C) and OS (D).

Fig. 2. Kaplan-Meier survival analysis of local control. A: When the tumor volume was smaller than 7 cm³, the local control rate of steretactic radiosurgery (SRS) was higher (p<0.001). B: If the time interval between diagnosis of anaplastic meningioma and SRS was shorter than 24 months, local control rate was statistically lower (p≤0.05). C: Although the marginal dose is not statistically significant, it shows a trend that is helpful for local control as it is higher.