Interstitial radiosurgery in low-grade gliomas

Abstract

The management of patients with low-grade gliomas remains a challenge. The natural course of the disease varies considerably and is highly influenced by treatment-independent factors such as age, pretreat-ment performance score, tumor volume, contrast-enhancement on CT/MRI, and tumor histology [10] (Fig. 1). Young patients with small, nonenhancing tumors, excellent performance score, and oligodendro-glial differentiation usually have favorable outcome scores (5-year survival rate in the range of 85%). The prognosis, however, dramatically decreases in the case of two or more unfavorable prognostic factors (5-year survival rates in the range of 10-40%). Given the strong impact of treatment-independent factors, it is not surprising that treatment effects are difficult to assess for patients with WHO grade II glioma. This problem has recently been highlighted by the results of three prospective randomized studies [4, 5, 19]: Neither early external beam radiation (after tumor resection or stereotactic biopsy) nor tumor dose escalation from 45 Gy to 59.4 Gy resulted in better survival rates. However, patients treated with higher tumor doses experienced more side-effects of the therapy in terms of the quality of life paradigm. Therefore, risk minimization must be the paramount aim in any treatment modality considered. Bearing this in mind, the growing interest in less invasive and more individualized (tailor-made) therapeutic approaches is not surprising. Over the last few years, stereotactic treatment modalities (i.e., interstitial radiosur-gery and stereotactic radiotherapy) as well as chemo-therapeutic regimens (for oligoastrocytomas and oligodendrogliomas) have gained in importance. © Springer-Verlag Berlin Heidelberg 2006.