Abstract:
The accumulation of fluorescent and phototoxic porphyrins upon administration of the precursor 5-aminolevulinic acid (5-ALA) has proven a high selectivity for malignant tumours, especially in the brain. This enables the intraoperative detection of residual tumour during surgical resection. The procedure has gained European clinical approval in 2007. The development from basic research to post-approval study results will be outlined. In addition, the phototoxicity of porphyrins can be exploited for tumour destruction. The most promising results so far have been obtained with a stereotactic approach, where a couple of radial light diffuser fibers are inserted into the brain tumor through small holes in the skull, based on a careful treatment planning. Taken together, the photodynamic procedures can be expected to significantly prolong the recurrence free survival time for patients suffering from this dismal malignant disease.  
Dr. Herbert Stepp
Laser-Forschungslabor, LIFE Center,
Klinikum der Universität München, 
Munich, Germany