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VII./4.5.: Treatment
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Surgical treatment. Neurosurgical method is the usual treatment of meningiomas. With the evaluation of modern microsurgical and navigation techniques, even the previously not operable tumors can be treated. Total resection aimed, if possible, with resection of the attached dural tissue and infiltrated skull bone as well. Surgical removal can be graded due to the resected tissues (Simpson stages): 1. stage total excision with the dura and bone resected, and (partial) venous sinus resection as well, if the tumor arise close to them; 2. Stage: total excision with the coagulation of the adjacent dura; 3. stage: total excision but insufficient dural attachment or bone-infiltration removal, e.g. because the infiltration of the skull base or sinuses; 4. stage: macroscopically residual tumor visible; 5. stage: biopsy, sample taken.
Parasagittal meningiomas close to the middle or posterior third of the superior sagittal sinus are difficult surgical cases, because for the sake of total resection to prevent recidive tumor, parts of the meningioma inside the sinus should be removed as well. After opening a partially occluded venous sinus followed by tumor resection, reconstruction of the sinus performed. Resection of the occluded part of sinus is also a possibility. In both situations, protection of the cortical veins is important, because venous cortical infarcts and bleeding occur if occluded. Coagulation or postoperative radiotherapy of the residual tumor is possible if total resection could not be performed because of anatomical situation and tumor growth into the sinus. In selected cases, endovascular embolisation can be performed preoperatively, in some inoperable cases that could be the only available and possible treatment.
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Radiotherapy. The opinions on radiotherapy are diverse; it is generally accepted in the treatment of atypical, anaplastic and recidive meningiomas and after subtotal surgery. Stereotaxic radiotherapy also available, used for treating small (smaller then three cm), benign, but technically inaccessible meningiomas.
Pharmacotherapy. Pharmacotherapy of meningiomas is mostly experimental, with different clinical practice in different centers.
Experience of chemotherapy based on case reports and small case series are not encouraging, chemotherapy show minimal effect. Chemotherapy is limited to some cases after surgical removal followed by radiotherapy is ineffective, and radiotherapy worn out. Dacarbazin/adriamycin or ifosphamid treatments were not successful. Temozolomide proved to be ineffective, likely because O6-methylguanin-DNA-methyltransferase activity detected in meningiomas, nearly always.
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Under experimental circumstances, irinotecan inhibited cell growth of meningiomas, but in phase II it failed. Hydroxyurea, an oral ribonucleotid-reductase inhibitor stops the mitosis of the meningioma cells in S phase and induce apoptosis. According to case reports, with the dose of 20mg/kg/day, size of the recidive meningiomas decreased, and in one case, a patient with malignant meningioma was recidive free for 2 years after operation. However, in phase II clinical trial, responder rate was below 5%. In some cases, alfa-interferon slowed the progression of meningiomas.
Hormonal therapy, e.g. oestrogen-receptor inhibitors did not prove to be effective, although slight positive result was experienced with tamoxifen. Progesterone-receptor inhibitor, anti-gestagen mifepristone could be useful in tumors expressing progesterone receptors, but did not show effect in the largest cases series experiment. Growth hormon receptor antagonists or somatostatin receptor antagonist may be promising, since meningiomas often associate with acromegaly.
Inhibition of angiogenesis could be a future therapeutic option; and a number of preclinical data are available altering molecular mechanisms of meningioma growth or invasion.
In a clinical trial, anaplastic meningioma treatment schedule included surgical resection and irradiation followed by adjuvant chemotherapy with cyclophosphamide, adriamicin and vincristin; in this trial, average survival was 5.3 years, and 4.6 years elapsed until tumor progression observed.
Perifocal oedema around the tumor requires medical treatment; convulsions have to be treated with anticonvulsive medications.
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