The prognosis for meningiomas following gross total resection depends on the histology. In a single series of 1799 meningioma specimens from 1582 patients followed for an estimated average of 13 years, 93.1% of benign meningiomas, 65.4% of atypical meningiomas, and 27.3% of malignant meningiomas were cured by surgery (Maier et al 1992). A study from Finland found the recurrence rate for benign meningiomas to be higher, with 19% recurring at 20 years (Jaaskelainen 1986). Another study of 9000 cases found the 5-year rate of recurrence to be 20.2% (McCarthy et al 1998). The larger series above shows a 5-year survival rate of only 70%, 75%, and 55% for benign, atypical, and malignant meningiomas, respectively (McCarthy et al 1998). A Mayo Clinic study noted a 25% 10-year recurrence rate in gross totally resected meningiomas, and a 61% 10-year recurrence rate in subtotally resected meningiomas (Stafford et al 1998). Median time to recurrence was 11.9 years for atypical meningiomas, and 2 years for malignant meningiomas. Five-year and 10-year survival was 81% to 95% and 58% to 79% for atypical meningiomas, and 60% to 64% and 35% to 60% for malignant meningiomas (Palma et al 1997; Coke et al 1998). Following subtotal resection of meningioma, radiation therapy decreases recurrence rate from 60% with surgery alone to 32% with radiation therapy, with a longer time to recurrence in the radiated group (Barbaro et al 1987). Tissue type alkaline phosphatase (Pa1) was studied in resected meningiomas and was found to be elevated in atypical and anaplastic meningiomas. Abnormal Pa1 expression correlated with recurrence (Bouvier et al 2005).
Research has investigated possible prognostic factors in atypical and malignant meningiomas specifically. In an analysis of 76 atypical meningiomas and 10 malignant meningiomas, high mitotic count, brain invasion, and parasagittal-falcine location were significantly associated with decreased recurrence-free survival (Vranic et al 2010). Also, Ki-67 index greater than 4% was also associated with decreased time to recurrence. These appear to be important pathologic indicators of aggressiveness of these tumor types.
In predicting recurrence and aggressiveness of meningiomas, the oncofetal protein IMP3 has been recently identified as a biomarker for tumor aggressiveness. One study looked at 107 patients with primary meningiomas (Hao et al 2011). Out of 13 patients with tumor recurrence, 7 patients expressed IMP3. They demonstrated that IMP3-positive tumors were significantly associated with a higher recurrence rate and poorer overall survival.
A recent study found anatomic location to also have prognostic significance (Kane et al 2011). They reviewed 378 patients with meningioma, looking for potential risk factors for high-grade pathology. They found that nonskull-base meningiomas, prior surgery, and male sex all increased risk of grade II or III pathology, which extrapolates to poorer prognosis and increased likelihood of recurrence.
In a study of neurocognitive functioning following surgery and radiotherapy, cognitive functioning 1 year post surgery was significantly impaired in the surgical group with no additional cognitive deficits in the group that received surgery plus radiotherapy (van Nieuwenhuizen et al 2007). The assessment time interval from radiotherapy may not have been great enough to adequately assess additional cognitive dysfunction from radiotherapy.
Metastasis from meningioma is uncommon. Benign meningiomas have rarely been reported to metastasize to the lungs and other organs (Miller et al 1985). Malignant meningiomas metastasize rarely; however, if they do, the lungs are the most common site followed by the abdominal viscera, bones, and lymph nodes (Rawat et al 1995). Breast, lung, and squamous cell carcinomas, as well as lymphoma, have been reported to metastasize to meningioma (Doron and Gruszkiewicz 1987). Cerebrospinal fluid dissemination of meningioma occurred in 4% of 200 consecutive meningiomas in the subarachnoid or ventricular location, and was coincident with multiple other metastatic sites (intracranial, spinal and extraneural) (Chamberlain and Glantz 2005).
In regards to prognosticating in children and adolescents, in the past, this was done by extrapolating from adult studies. However, a recent meta-analysis was performed in order to provide further insight into the clinical evidence regarding meningiomas in children and adolescents (Kotecha et al 2011). They found that the strongest independent predictor of prognosis in these subjects was extent of the initial surgical resection, indicating that the goal should be gross total resection. Additionally, patients with NF2 seem to have a poor prognosis in long-term follow-up, warranting lifelong follow-up in this subset of patients.