PHOTODYNAMIC THERAPY IN NEUROSURGERY - A REVIEW

Photodynamic therapy (PDT) has been investigated extensively, both exp erimentally and clinically, as an adjunctive treatment in the neuro-on cological held. It is based on the more selective accumulation of a ph otosensitizer in malignant than normal tissue with low systemic toxici ty. Subsequent light activation induces photo-oxidation, followed by s elective tumour destruction via vascular and direct cellular mechanism s. Malignant brain tumours carry a lethal prognosis with a median surv ival of 15 months despite surgery, radiotherapy and chemotherapy. PDT is therefore a logical therapeutic concept for brain tumours infiltrat ing into normal brain. In this review, all the available data on patie nts treated with haematoporphyrin derivative-mediated PDT are critical ly analysed. Over 310 patients have been reported in the literature su ffering from primary or recurrent malignant brain tumours which were t reated with PDT following tumour resection in open clinical phase I/II trials. This number includes 58 patients treated at our own instituti on. Variations in the treatment protocols make evaluation scientifical ly difficult; however, there is a clear trend of increased median surv ival after surgical resection and one single photodynamic treatment. P DT is generally well tolerated and side effects consist of moderate in creased intracranial pressure and prolonged skin sensitivity to direct sunlight. The current available data indicate that PDT is a safe trea tment, which is well tolerated by the patients and yields an improveme nt in survival of those with malignant brain rumours. Conclusive infor mation can be expected from controlled clinical trials which are curre ntly being designed. The results raise the hope that PDT will be a val uable addition to the armamentarium for the treatment of cerebral mali gnancies.