Michael Weber is a medical practitioner for more than 20 years in Germany and leader of three medical centers for general and internal medicine, pain and cancer treatment. Furthermore he is a certified bio-chemist and medical doctor. He is working in research with many national and International institutions and universities. He is president of the International society for Medical Laser applications and editor in chief of the Inter-national Journal for Medical Laser applications. He is also Co-editor of several other journals.
Photodynamic therapy is one of the most promising therapeutic approaches in oncology. The therapeutic procedures are not complicated and in contrast to traditional chemotherapy without severe side-effects if applied correctly. The principle is the stimulation of a light sensitive substance which is injected into the bloodstream or directly into the tumor.
After approx. 3 hours the photosensitizer will be integrated into cancer cells by endocytosis and leads to a light sensitivity of those cells. By irradiation of laser light with wavelengths according to the absorption spectra of the photosensitizers, the tumor cells will be destroyed by reactive singlet oxygen radicals.
The therapeutic effect can be enhanced by combination with intravenous or hyperbaric oxygen therapy or by hyperthermia. Today 3 different photosensitizers are used for PDT: Chlorin E6 with red laser stimulation, Hypericin (yellow laser) and Curcumin (blue laser). All substances are available for intravenous injection or infusion. The newest development is Indocyanine green (ICG) in a liposomal form which is the first photosensitizer stimulated by infrared light with much deeper tissue penetration (even through bones).
The stimulation can be performed intravenously, interstitially and intratumorally using a new fiber-optic catheter technology. A combination with low-dose chemotherapy using chemo drugs as photosensitizers can be used in metastasized cancers (combination of traditional chemotherapy with new photodynamic procedures). Basic principles on the one hand and treatment results, on the other hand, will be presented. In contrast to traditional high dose chemotherapy, PDT does not only destroy cancer cells but also initiates a lot of different reactions in the treated area with a stimulation of the immune system (PDT-immunization).
The limitation of PDT for treatments only for external tumors can be overcome by the described new methods and opens up a comprehensive application of PDT in most human cancers.