Interstitial iodine-125 radiosurgery for cerebral metastases.

The current study evaluates the efficacy of interstitial 125-iodine radiosurgery (brachytherapy) in 93 patients with circumscribed, spherical, mostly solitary metastases. In all patients the histological diagnosis was established by stereotactic biopsy. The treatment results of three therapeutic regimens have been examined retrospectively: Group A (38 patients) had interstitial radiosurgery with a reference tumour dose of 60 Gy in combination with percutaneous radiotherapy (40 Gy). Group B (34 patients) was treated by interstitial radiosurgery alone (reference dose 60 Gy). Group C (21 patients with recurrent metastases after previous radiotherapy/surgery) was treated by interstitial radiosurgery alone (reference dose 60 Gy). Median survival after interstitial radiosurgery was 17 months in group A, 15 months in group B, 6 months in group C. Favourable prognostic factors were a Karnofsky performance rating > or = 70, solitary metastasis, absence of disseminated disease, and a time interval > 1 year between diagnosis of the primary tumour and diagnosis of the cerebral metastases. Interstitial radiosurgery plus percutaneous radiotherapy did not prove to be superior to interstitial radiosurgery alone. No patient died of a locally irradiated metastasis. We conclude that interstitial radiosurgery achieves control of the growth of solitary spherical cerebral metastases in any location without radiation toxicity.