Many trials have been published or are under way concerning a variety of new approaches: the selection of patients for chemotherapy based on methyl guanine methyl transferase (MGMT) status, convection-enhanced delivery of ‘old’ and new drugs, macrotoxins, antiangiogenic drugs, pathway inhibitors and immunotherapy, etc. In most studies, little attention has been paid to the role of surgical resection. Even when a sub-analysis of the role of biopsy versus resection is performed, or when upfront stratification is carried out concerning the radicality of surgical removal, the definition of that radicality is poorly defined, seldom quantified and often based on, and consequently biased by, the surgeon’s impression.

However, there are a few studies in which the size of the resection has been measured carefully, and in which an analysis has been made of the effect of resection (or residual tumour) on overall survival (OS), progression-free survival (PFS) and quality of life (QOL). The results all point towards a positive – and in some studies significant – effect on these three factors.^2,3 Furthermore, after sub-analyses on some of the recent drug studies (especially the Stupp study with temozolomide), the conclusion may be made that even when ‘radical resection’ per se does not add too much to survival, the effects of adjuvant therapy, e.g. the chemo-radiation regime, seem to be positively influenced by resection.⁴ This forms the rationale for attempts to improve radicality in neurosurgical tumour resection.

Radical Resection and Fluorescent Guidance
Surgical approaches aiming at ‘maximal’ or ‘radical’ resection include neuronavigation (with definite limitations due to shifts) and intra-operative magnetic resonance imaging (MRI), computed tomography (CT) or ultrasound, in addition to the experience of surgeons with direct visualisation and tissue ‘feeling’ techniques. Such procedures, though effective, are expensive and also have limitations regarding interpretation.

A promising but simpler method to reach more radical resections seems to be the use of a vital staining of tumour tissue, which can be used in the operating theatre. A group of German neurosurgeons, under the guidance of Stummer and Tonn, have proved over the last few years that a prodrug to protoporphyrin IX, 5-amino levulinic acid (5-ALA), works in this way.⁵ It is a naturally occurring compound in the human body, but when given in a large amount it is accumulated preferentially in the skin and in certain malignant tumours, especially high-grade gliomas. When cells stained by synthesised protoporphyrin IX are illuminated with a special light (blue, wavelength 375–440nm), they show fluorescence with a red/pinkish light at a wavelength of 635nm, which makes them easily recognisable. The precursor 5-ALA is given to patients by the oral route a few hours before surgery.