BACKGROUNDComplete tumour resection is important for improving the prognosis of brain tumour patients. However, extensive resection remains controversial because the tumour margin is difficult to be distinguished from surrounding brain tissue. It has been established that 5-amino-4-oxopentanoic acid (5-aminolevulinic acid, ALA) can be used as a photodynamic diagnostic marker and a photosensitizer for photodynamic therapy in surgical treatment of brain tumours. We investigated the efficacy of ALA photodynamically guided microsurgery and photodynamic therapy on VX(2) brain tumour implanted in a rabbit model.

METHODSEighty New Zealand rabbits implanted with VX(2) brain tumours were randomly assigned to five groups: control, conventional white light microsurgery, a photodynamic therapy group, a photodynamically guided microsurgery group and a group in which guided microsurgery was followed by photodynamic therapy. The VX(2) tumour was resected under a surgical microscope. The tumour resection was confirmed with histological analysis. All animals were examined with MRI for presence of any residual tumour tissue. The survival time of each rabbit was recorded.

RESULTSAll treatment groups showed a significantly extended survival time compared with the control group. Photodynamically guided microsurgery combined with photodynamic therapy significantly prolonged survival time, compared with guided microsurgery alone. MRI and the autopsy results confirmed removal of most of the tumours.

CONCLUSIONSOur results suggest that photodynamically guided surgery and photodynamic therapy significantly reduce or delay local recurrence, increase the effectiveness of radical resection and prolong the survival time of tumour bearing rabbits. Their combination has the potential to be used as a rapid and highly effective treatment of metastatic brain tumours.