Photodynamic therapy: a promising alternative in oncology

Photodynamic Therapy (PDT) is a treatment modality that is based on the administration of a photosensitizer and the following application of light in a wavelength range matching the absorption spectrum of the photosensitizer. Ideally the photosensitizer retains in the tumor tissue more than in normal tissue and thus allows targeted destruction of cancerous tissue. The use of PDT is slowly being accepted as a standard treatment for certain types of cancer. This includes mainly treatment strategies with only palliative intentions (obstructive esophageal cancer and advanced lung cancer) while for certain malignant conditions new applications exists that are already intended for cure (e.g. early stage of lung cancer). The main advantage of PDT is that the treatment can be repeated multiple times safely without major side effects. PDT can be safely combined with already established treatment options like surgery, chemotherapy or radiotherapy. A disadvantage of PDT is the only localized effect of the therapy, which usually cannot significantly alter the outcome of a systemic disease. In this paper we review the history of PDT as well as current clinical applications in oncology and future directions.