Photodynamic therapy: Palliative and curative aspects

Photodynamic therapy (PDT) is based on the interaction of tumor-selective p hotosensitizers and laser light. This interaction causes selective death of tumor cells. For palliative intention, PDT in comparison to Nd:YAG laser i s approximately equally effective in relieving endobronchial obstruction by tumor. The time to treatment failure is slightly longer after PDT than aft er Nd:YAG laser resection, and the risk of reobstruction after PDT is lower than after Nd:YAG therapy. Additionally, PDT in most cases can be performe d with flexible bronchoscopes and local anesthesia because there is no disc omfort or significant risk during intervention. Compared to Nd:YAG laser re canalization PDT, however, has no immediate effect and therefore is not sui table for treatment of acute respiratory failure. For centrally located ear ly lung cancers, treatment of incurative intention, the histologically conf irmed complete remission rate 3 weeks after PDT is about 90%. However, over a long-term, only 50-70% of the patients remain stable. Therefore, PDT wit h curative intention does not achieve the success rates of surgical treatme nt with more than 80% and should be performed only in inoperable or high-ri sk patients. A main disadvantage of PDT is a prolonged photosensitization o f skin and eyes. Strict protection from the sun is essential to avoid sever e reactions. For patients, treated with palliative intention, with a mean s urvival of only 2-3 months, this means a severe reduction of quality of lif e. For patients with early-stage cancers treated with curative intention, t he photosensitization of skin is less important in relation to the long mea n survival time of these patients.