5th World Congress on Cancer Therapy
Laser Clinic Dr. Weber, Germany
Title: Systemic and interstitial photodynamic laser therapy: New options in oncology
Biography: Michael Weber
Photodynamic therapy is one of the most interesting and promising approaches in the treatment of various cancers. Treatmentsrnare easy to perform and – in contrast to chemotherapy – normally without severe side-eff ects. Th e principle is the stimulationrnof a light-sensitive drug which is injected into the blood. Th rough endocytosis, the photosensitizer binds to tumour cells anywherernin the body with high specifi city. Th e process takes several hours and tumour cells will have turned light sensitive at the end.rnTumour tissue is subsequently destroyed by irradiation with light of appropriate wavelength according to the absorption spectra ofrnthe various photosensitizers. Th e basic principle behind this mechanism is the development of radical oxygen species.rnIn contrast to traditional chemotherapy PDT does not only destroy cancer cells by oxygen radicals but also initiates a lotrnof diff erent reactions in the treated area with a stimulation of the immune system (PDT-immunisation). Photosensitizers arernmostly porphyrin molecules and derivatives either from the human heme (without the iron atom) or plantderived chlorophyllrn(without the magnesium atom). Accordingly, they are called hematoporphyrins or chlorines. Some are already approved and usedrnin therapy, e.g. Photofrin for treatment of early stage bronchial and gastric cancer.rnRed (in most cases), blue or yellow light is used for light activation of photosensitizers either from outside or through anrnendoscope. Due to the limited penetration depth of light eff ective photosensitizer stimulation and tumour destruction can onlyrnbe achieved at the surface of the skin or in the tissue just a few centimetres underneath the skin. An eff ective treatment of deeprntumours or metastases (e.g. liver cancer or lymph nodes) has normally not been possible and therapeutic applications have so farrnbeen primarily used to treat dermatological tumours. Due to this limitation, progress has been slow until recently.rnToday, new technological developments that facilitate systemic and interstitial photodynamic therapies overcome this barrierrnand constitute the basis for massive growth in the fi eld. Th e lecture will focus on presenting the new technology of systemic andrninterstitial photodynamic laser therapy, newest photosensitizers (with very specifi ty and low side-eff ects) and clinical results fromrnthe last few years of research and development in Germany.