gms | German Medical Science

Objective: Intra-operative radiation therapy (IORT) refers to the delivery of single dose irradiation to a surgically exposed tumor at the time of the operation. The PRS employs a miniature x-ray generator which produces a radiation field similar to that of a low-energy brachyterapy source but with a delivery speed typical of external-beam radiosurgery. The aim of IORT is to sterilized malignant cells in the tumor bed, the main source of post-operative recurrence leading to treatment failure.

The aim of this study is to verify the useful of IORT for the treatment of glioblastomas (GBM) recurrences.

Methods: Since march 1999 54 patients were treated by IORT (glioma grade II, III, IV, metastases, malignant meningiomas). 21 patients (median age, 46,5 years; range, 22 to 69 years) were affected by GBM recurrent after microsurgical removal and external radiotherapy. A Karnofsky index >70 was a pre-requisite.

IORT was possible inserting the probe of miniature x-ray source into spherical applicators with diameters ranging from 1,5 to 5 cm. Doses from 8 to 15 Gy at 5 mm depth from the tumor bed were delivered after tumor removal. Delivery of the prescribe dose takes typically 10 to 45 minutes.

Follow-up >6 month was obtained in 18 patients.

Results: The median survival in 15 patients was 9,7 months (from 3 to 19 months). 3 patients are alive respectively 18, 13 and 7 months after the treatment. 1 year survival rate was 50% in 18 patients treated. 2 patients presented brain edema with a good recovery after steroid therapy. No infections were observed.

Conclusions: These preliminary results demonstrate that IORT is an effective adjuvant treatment of GBM recurrence after microsurgical removal.