[Iridium 192 brachytherapy of supra-tentorial high grade glioma recurring in irradiated areas: technique and preliminary results of the Pitié-Salpêtrière hospital group].

UNLABELLED: Our aim was to analyse feasibility and preliminary results obtained with iridium 192 re-irradiation of recurrent high grade gliomas.

MATERIAL AND

METHODS

a technique for implanting rigid plastic tubes afterloaded with iridium 192 wires was developed that utilised a stereotactic Leksell frame. Nineteen glioblastomas and one anaplastic glioma (12 males and 8 females: age: 20-69 years, median: 50) were implanted between January 1993 and December 1994. Previous treatments included surgery (18/20). 55-60 Gy external beam radiotherapy (20/20), and chemotherapy (16/20); interval between initial treatment and retreatment with iridium 192 was 6 to 39 months (median: 10). Maximum diameter of the tumour at the moment of implantation was 2.1-10.1 cm (median: 6.4 cm) and tumour volume 2.122 cm3 (median: 22 cm3). All tumours were supra-tentorial (right hemisphere: 9; left hemisphere: 11). Karnofsky index was 60-100 (median: 80). Implantation was carried out under local anaesthesia; tumour contours were visualised using either a CT-scan (16/20) or a MRI (4/20). Dosimetry was carried out using two orthogonal films and CT-scan images. Total dose on the reference isodose was 40-60 Gy (60 Gy: 9; 50 Gy: 7; 40 Gy: 4); dose-rate was 0.24-0.73 Gy/h (median: 0.38).

RESULTS

probability of overall survival is 90% at 6 months, 55% at one year, and 26% at two years. Median survival is 56 weeks. Eleven patients died from local failure, and three from leptomeningeal metastasis. Six patients are alive, 15-30 months after the implantation. Two were reoperated for brain necrosis. Three patients showed evidence of bacterial meningitis, and three others of skin necrosis.

CONCLUSION

according to this preliminary analysis, results obtained after reirradiation of high grade gliomas with iridium 192 are encouraging. More patients and longer follow-up are needed to draw definitive conclusions.