External beam and conformal radiotherapy in the management of gliomas

External beam radiotherapy remains an important local treatment modality in both high and low grade gliomas, however its contribution to outcome remains modest. In high grade tumours this is because of their extreme clinical radioresistance, with local recurrences occurring even after doses over 70 Gy. In low grade tumours radiation does not seem to alter the overall pattern of disease progression significantly. Therefore despite use of the new technologies now available that allow radiotherapy to be delivered more accurately and to higher doses, local control of these tumours is still rarely achieved. Unfortunately these tumours have not proven sensitive to changes in radiotherapy fractionation or to the addition of radiosensitising agents. Novel approaches to these tumours are needed, based on an improved understanding of both tumour and normal tissue response to radiation.