Photodynamic therapy: applications in bladder cancer and other malignancies

Photodynamic therapy (PDT) has gained popularity in the past 10 years because of advances in laser and pharmacokinetic technologies and the development of new photosensitizers. Early studies on PDT with focal illumination for papillary bladder cancer obtained reasonable response rates for small tumors but recurrence was common. Whole bladder irradiation, once a suitable light-delivery system had been developed, gave promising outcomes with acceptable rates of complications. PDT for prostate cancer is still at the experimental stage but initial results have been promising. Clinical trials of PDT for brain tumors have shown no significant complications but no improvement in survival rate compared with other treatment modalities. PDT is particularly useful for early superficial lung cancers that are localized to one or a few discrete sites; it is also safe to use in patients who are too sick to be treated with conventional therapies. Preoperative PDT has reduced the extent of surgery necessary in some patients. Clinical experience with PDT for gynecological cancer is limited and prospective studies are needed. In head and neck oncology, PDT should prove a useful option, but methodological problems need to be overcome. Good responses of esophageal cancer to PDT have led to governmental approval of Photofrin, a photosensitizer, in several countries for either palliative use or treatment of inoperable or recurrent cancer. The use of PDT for early gastric cancer has great potential but several technical problems remain. PDT has proven generally effective for skin cancer when hematoporphyrin derivative or Photofrin is used but more long-term follow-up data are required for PDT with 5-aminolevulinic acid. Overall, PDT is changing from a scientific curiousity into an accepted modality for the treatment of cancer, with an improved likelihood of finding further clinical applications.