Role of nuclear medicine in the treatment of malignant gliomas: the locoregional radioimmunotherapy approach

The high-grade malignant gliomas (anaplastic astrocytomas and glioblastoma) have a very bad prognosis since the available methods of treatment (surger y, radiotherapy and chemotherapy) are unable to control the progression of the disease for long. The use of specific monoclonal antibodies labelled wi th a suitable isotope (iodine-131 or yttrium-90) represents an effective ap proach to hamper tumour regrowth. Some authors have injected the antibodies intravenously, or have tried to increase the tumour/background ratio with the avidin/ biotin system. In many cases the labelled monoclonal antibodies were injected directly into the tumoral bed after the operation. The autho rs' experiences concern a quite large locoregional radioimmunotherapy study which was performed by using antitenascin antibodies labelled initially wi th I-131 and more recently with Y-90. The clinical results demonstrate the ability of this technique to control, for a long time, the growth of these tumours. The glioblastoma median survival was prolonged to 25 months (I-131 group) or 31 months (Y-90 group). The response rate (which comprises PR, C R and NED) was 47.1% (glioblastoma I-131 group) or 40% ( glioblastoma Y-90 group). In many cases a significant tumour shrinking effect was radiologica lly demonstrated. The use of Y-90 proved more favourable ill bulky lesions, and reduced the radioprotection problems.