Guidelines to the treatment of meningioma.

Epidemiology: Meningiomas constitute the largest subgroup of all intracranial tumours. Their incidence is about 2-3/100,000/yr, with a 3:2 to 2:1 female:male ratio, with a peak incidence in the sixth and the seventh decade of life. Meningiomas are usually slow growing, benign neoplasms, causing symptoms by compression of adjacent structures or by increased cranial pressure, the specific symptoms depending on the location of the tumour.

Risk factors: Meningiomas can be induced by radiation to the head, even by low dose radiation as used for dental radiographic examination after up to 35 yrs interval. The female preponderance in meningioma patients as well as the expression of progesterone receptor on the cell membranes of more than 50% of meningiomas is argument for an influence of gestagene in meningioma proliferation. The most frequent genetic predisposition of meningiomas is associated with neurofibromatosis 2 (NF-2); at least 40% of meningiomas show a deletion in the NF-2 gene.

Treatment: To date, surgical resection is the mainstay of meningioma therapy. The completeness of the resection is the single most important prognostic factor for recurrence. In case of incomplete resection or recurrence, radiation therapy with 54 Gy (1.8 to 2 Gy/fraction) yields comparable results to total resection. Radiosurgery is a valuable alternative to radiotherapy (RT), maybe in the future also for surgery, as recently demonstrated. In the rare meningioma patients, that have exhausted the possibilities of surgery and RT, there have been some successful small series using hydroxyurea or interferon alpha. Future therapeutic options might consist in octreotide isotopic therapy or targeted therapy directed against tumour neo-angiogenesis or other proliferation associated markers in meningiomas.