Photodynamic therapy. Biology and clinical application

PDT appears capable of treating small, superficial, endoluminal tumors. As the therapeutic light penetration currently goes no further than 1 cm, bulky neoplasms will remain resistant to this form of therapy. Second-generation photosensitizers that are activated by light wave-lengths with greater tissue penetration are under development. Similarly, solid-state lasers that require minimal maintenance and facilities are becoming available. Randomized trials comparing PDT with laser thermal ablation are underway. PDT will likely find a niche in the treatment of superficial tumors.