[Photodynamic destruction of in vitro cultivated squamous cell carcinoma cells of the head and neck area].

Hematoporphyrin derivatives are retained in higher concentrations in proliferating tumor tissues than in normal tissues causing a defined photosensitization. Laser light irradiation of photosensitized cells results in photobiological, non-thermal cell destruction. These photodynamic reactions were analyzed with in vitro cultured squamous cell carcinoma lines of the head and neck. As a light source we used an argon-ion-pumped-dye laser (630 nm wavelength), and for photosensitization we employed a mixture of dihematoporphyrinester and -ether (DHE). The photodynamic reaction on squamous carcinoma cells was proportional to the DHE concentration, the DHE incubation time, and the light exposure. Maximal tumor cell destruction in comparison to DHE free controls was observed with DHE concentrations of 5-10 micrograms/ml medium and a light exposure of 2-4 Joule/cm2. Based on these dose effect relations for DHE sensitized squamous carcinoma cells, photodynamic therapy for destruction of head and neck cancer can be applied in animal tumor models.