Intensity-Modulated Radiation Therapy (IMRT) for Newly Diagnosed and Recurrent Intracranial

www.tcrt.org 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 insti-tution with the NOMOS Peacock system utilizing the Multileaf Intensity Modulating Collimator (MIMiC). Thirty-five patients with 37 lesions (35 benign and two atypical histol-ogy) were identified with a minimum of six months of radiologic follow-up for this retrospec-tive 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 pri-marily 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 com-pared 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 analy-sis, these factors did not remain significant for influencing local control. No long-term com-plications from IMRT were documented among the 35 patients. In conclusion, intensity-modulated radiation therapy is a safe and effective treatment for some intracranial menin-giomas. A greater number of patients with longer follow-up after treatment may be needed to determine treatment variables predicting for long-term tumor control. Key words: Meningioma; Intensity-modulated radiation therapy; and Local control