Radiotherapy to volumes defined by metabolic imaging in gliomas: time to abandon monstrous margins?

The survival in patients with high grade gliomas (HGG) remains poor even after the adoption post-operative radiotherapy (RT) to magnetic resonance imaging (MRI) based volumes. Despite delivery of ‘standardized’ doses of radiation, recurrence is the norm, rather than the exception. Recurrences occur both within, and outside of the volume of irradiation, leading us to two questions—firstly concerning the adequacy of the dose of radiation used, and secondly about the current methods of treatment volume delineation. The emergence of newer radiopharmaceuticals for use in positron emission tomography (PET) have kindled the hope of more precise volume localizations for post-operative RT, and it is likely that these new radiopharmaceuticals can help us define accurate areas at highest risk of recurrence and thus allow us to use increased doses of radiation with confidence.