Revised: June 2014
Meningiomas are graded using the WHO grading system. Most meningiomas are grade I with a low proliferative rate. Grade II or atypical meningiomas typically feature an elevated mitotic activity (>4 mitoses per 10 high power fields) whereas grade III or malignant meningiomas show very aggressive features with markedly increased mitotic activity (>20 mitoses per 10 HPF) and brain invasion (1).
Not infrequently, a meningioma may be an accidental radiologic finding on CT scan or MRI booked for various reasons. Where the disease is asymptomatic less than two cm in size and not associated with edema and particularly in patients who are more than 60 years old, observation may be a reasonable approach with annual clinical examination and CT scan. A majority of the other patients and patients who demonstrated radiologic and clinical progression of the tumour are treated surgically. Total excision is usually achieved in tumours located in the convexity dura, falx, lateral aspects of sphenoid wings, frontal base and cerebellar convexity. If pathology demonstrates WHO grade I meningioma after total excision, no further treatment is indicated and the patient should be continued on observation with yearly examination and CT scan. Local recurrence rate, however, varies from 8% to 20% over 10 years (2) and patient may require further re-excision with consideration of radiotherapy.
In other locations, gross total excision may not be possible (sagittal sinus, cerebellopontine angle, clivus, cerebral ventricles, tentorial notch, optic nerve sheath). Local recurrence rate for partially excised meningioma varies from 29% to 55% over 10 years (2), and postoperative radiotherapy always should be considered (it is available in the form of conventional/conformal or stereotactic radiotherapy). Local control rate after postoperative radiotherapy for meningioma is 87% over 15 years (3,4,5).
In case pathology demonstrated WHO grade II meningioma, postoperative radiotherapy should always be considered. Local control rate drops down to 54% for atypical meningiomas (3,4,5).
Malignant meningioma (12% of meningiomas) should be treated aggressively with surgery and postoperative radiotherapy. Investigations, apart from assessment of primary site, should include CXR and bone scan to rule out lung and bony metastasis. Prognosis for this group of patients is poor and five year specific survival is only 34%(6).
There is currently no standard systemic therapy for recurrent unresectable meningioma. Trials of chemotherapy, interferon, progesterone inhibitors, somatostatin analogs, and anti-VEGF therapy have not shown evidence of altering disease outcomes but have occasionally shown some alteration of disease progression (7).
References:
Perry, A, Louis, DN, Scheithauer, BW, et al. Meningiomas. In: WHO Classification of Tumours of the Central Nervous System, Louis, DN, Ohgaki, H, Wiestler, OD, Cavenee, WK (Eds), IARC Press, Lyon 2007.
Mirimanoff R.O, et al: Meningioma: Analysis of Recurrence and Progression Following Neurosurgical Resection. J. Neurosurgery 62:18-24. 1985.
Glaholm J, Bloom H.J.G: The Role of Radiotherapy in the Management of Intracranial Meningiomas: The Royal Marsden Hospital Experience with 186 Patients. I.J.R.O.B.P. 18(9):755-761. 1990.
Condra K.S, et al: Benign Meningiomas: Primary Treatment Selection Affects Survival. I.J.R.O.B.P. 39(2):427-436. 1997.
Maire J.P, et al: Fractionated Radiation Therapy in the Treatment of Intracranial Meningiomas: Local Control, Functional Efficacy and Tolerance in 91 Patients. J.J.R.O.B.P. 33(2):315-321. 1995.
Milosevic M.F, et al: Radiotherapy for Atypical or Malignant Intracranial Meningiomas. I.J.R.O.B.P. 34(4):817-822. 1996.
Norden AD, Drappatz J, Wen PY. Advances in Meningioma Therapy. Curr Neurol Neurosci Rep 9:231, 2009.
