Atypical meningioma: a study of prognostic factors.

Objective: Atypical meningiomas represent 20% of all meningiomas. This retrospective study analyzes the prognostic factors, the effect of different methods of treatments, and the behavior of atypical meningiomas.

Methods: The study comprised 44 patients who were given a diagnosis of atypical meningioma according to the 2007 World Health Organization classification in the period from January 2009 to March 2012. Data collected included patient age, gender, tumor location, presenting symptoms, and treatment received. Patients were followed to detect recurrence and assess survival.

Results: Median overall survival was 57 months, with a 5-year survival of 35%. Significantly better survival was observed for patients <50 years old (65 months vs. 46 months, P = 0.033) and patients with total resection (Simpson grade 1-2) compared with subtotal resection (Simpson grade 3-4) or biopsy (Simpson grade 5) (75 months vs. 46 months and 24 months, P < 0.0001). Patients with a tumor located in brain convexity had better survival but with no statistical significance (P = 0.052). Multivariate analysis showed prognostic significance with age (P = 0.030) and extent of resection (P < 0.000). Progression-free survival ranged from 7-83 months with a median of 39 months. Progression-free survival showed a significant relationship with subtotal resection compared with biopsy (P = 0.007). Recurrences were less in patients who received radiotherapy (RT), and this was statistically significant (P = 0.007).

Conclusions: Long-term survival is possible for patients with atypical meningiomas treated with surgery and postoperative RT. Multivariate analysis confirmed that age (<50 years) and total surgical excision were independent prognostic factors for survival. Adjuvant RT reduces tumor recurrence, especially after incomplete surgery.