Photodynamic therapy of brain tumors.

Photodynamic therapy (PDT) is a binary treatment modality suitable for various malignant tumors including brain. It involves the selective uptake of a photosensitizer into tumor followed by intraoperative irradiation of the tumor with light of an appropriate wavelength to cause activation of the sensitizer and subsequent selective tumor destruction. PDT has been extensively investigated in laboratory studies and has been used in clinical trials to treat a variety of brain tumors, particularly gliomas. The main advantage of PDT lies in its ability to select out infiltrating tumor cells that are responsible for local tumor recurrence. The therapy has been shown to be safe clinically but adequate trials have yet to be undertaken to prove its efficacy and much work remains to be done to optimize treatment. The biological basis, laboratory studies, and clinical trials involving PDT in the treatment of cerebral tumors are discussed.