Photodynamic therapy for head and neck cancer xenografts in athymic mice.
This study examines efficacy and optimal treatment variables of photodynamic therapy (PDT) for human head and neck squamous cancer (HNSC) xenografts in athymic mice. Two and four days after injection of hematoporphyrin derivative (HPD), tumors were illuminated with red light from an argon-dye laser. Sixty-three tumors were treated. With HPD dose and light intensity constant at 7.5 mg/kg and 100 mW/cm2, respectively, the extent of tumor necrosis was strongly dependent on duration of light exposure. There was no substantial difference in results for 30- and 60-minute treatment durations between animals injected with HPD 2 and 4 days before treatment. After 30 minutes treatment time, responses were seen in 8 of 10 mice (2 days post-HPD) and 11 of 12 mice (4 days post-HPD). After 60 minutes treatment time, toxicity was high. We conclude that, in this model, PDT is effective in selective killing of HNSC. For future comparison studies in this model, if the indicated HPD dose and light intensity are used we recommend a 2-day delay after HPD injection and a light exposure duration of 30 minutes.
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy*; D006258:Head and Neck Neoplasms / Q000188:drug therapy*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D010778:Photochemotherapy; D013997:Time Factors; D014183:Transplantation, Heterologous