Photodynamic therapy: a new approach to prostate cancer.

Photodynamic therapy (PDT) is based on the concept that light irradiation can change an inert substance into an active one. In urology, hematoporphyrin derivative (HpD) and Photofrin (Axcan Scandipharm Inc., Birmingham, AL) are used most commonly as photosensitizing agents predominantly for the treatment of transitional cell carcinoma of the bladder. To investigate the basics for PDT of prostate cancer, several studies were performed on the optical characteristics of prostate tissue and prostate carcinoma tissue in vitro and in vivo and on the penetration depths of different laser wavelengths. Initial experimental studies to treat prostate cancer with PDT using HpD were done on Dunning tumors in rats. Combined with interstitial applicators, photodynamic therapy seems to have a great potential in the treatment of prostate carcinoma. However, it is an experimental treatment and even a preliminary evaluation will be possible only after the conclusion of clinical studies with the corresponding long-term results.