Intensity-modulated radiation therapy (IMRT) for newly diagnosed and recurrent intracranial meningiomas: preliminary results.

The purpose of this study was to evaluate tumor control, complications, and outcome from intensity-modulated radiation therapy (IMRT) for intracranial meningiomas. Between July 1997 and November 2003, patients with intracranial meningiomas were treated at our institution with the NOMOS Peacock system utilizing the Multileaf Intensity Modulating Collimator (MIMiC). Thirty-five patients with 37 lesions (35 benign and two atypical histology) were identified with a minimum of six months of radiologic follow-up for this retrospective review. The median age of the patients was 65 years with a median KPS of 90 prior to treatment with IMRT. The median MRI/CT follow-up for the 37 treated lesions was 19.1 months (range 6.4-62.4 months). Twenty meningiomas (54%) were previously treated with surgery/radiosurgery prior to IMRT, and 17 meningiomas (46%) were treated with IMRT primarily after diagnosis was established by MRI/CT. The median time from previous surgery to treatment with IMRT was 18.1 months. The median tumor dose was 50.4 Gy prescribed to the 87% isodose line providing a median target coverage of 95%. Local control was at 97% three years after treatment with IMRT. Only three patients exhibited local failure after treatment. Although local control was slightly better in the upfront-IMRT lesions as compared to the lesions treated with prior surgery/radiosurgery (100% vs 95%), this difference was not statistically significant. On univariate analysis, the IMRT prescription dose and maximum dose were found to be predictors for local control (p=0.05). On multivariate analysis, these factors did not remain significant for influencing local control. No long-term complications from IMRT were documented among the 35 patients. In conclusion, intensity-modulated radiation therapy is a safe and effective treatment for some intracranial meningiomas. A greater number of patients with longer follow-up after treatment may be needed to determine treatment variables predicting for long-term tumor control.