Lack of efficacy of megestrol acetate in the treatment of unresectable meningioma.

The detection of hormone receptors on meningiomas raises the possibility of hormonal manipulation as a form of therapy. Since progesterone receptors are found on meningiomas more frequently and in greater amounts than estrogen receptors, manipulation of progesterone levels would be most promising. A trial of the oral progesterone agonist megestrol acetate for the treatment of unresectable meningioma was therefore performed. Megestrol acetate was administered at a dose of 40 mg four times daily which could be escalated to 80 mg four times daily. Nine patients (six meningothelial, two fibrous, and one anaplastic meningiomas) were treated for 1 to 12 months. No tumor responses were seen. However three patients required discontinuation of therapy due to deteriorating vision within 2 1/2 months. The major systemic toxicity of megestrol acetate was weight gain with a median weight gain of 14 kg for patients treated for at least 6 months. Due to the lack of efficacy and the significant toxicity noted, megestrol acetate is not recommended for the treatment of meningioma. However clinical trials of progesterone antagonists would still be of interest.