Treatment of canine oral squamous cell carcinomas with photodynamic therapy

Eleven dogs with naturally occurring oral squamous cell carcinomas were tre ated with photodynamic therapy (PDT) using Photochlor (HPPH) as the photose nsitizer. The largest length of the tumours measured in a two-dimensional p lane ranged from 0.9 to 6.8 cm, Seven of the tumours invaded underlying bon e as determined by radiograph appearance. Photochlor was injected intraveno usly at a dose of 0.3 mg kg(-1). Forty-eight hours later the tumours were t reated. Tumours with a surface to base depth of greater than 1 cm were surg ically reduced to less than 1 cm. Irradiation with 665 nm light with an ene rgy density of 100 J cm(-2) was administered. Eight dogs were considered cu red with no tumour recurrence for at least 17 months after treatment, Local treatment of oral squamous cell carcinomas with PDT appears to give result s similar to those obtained with surgical removal of large portions of the mandible or maxilla. The cosmetic results with PDT are superior to those of radical surgical removal. The new sensitizer, Photochlor, appears effectiv e for oral squamous carcinomas with results similar to those reported for o ther sensitizers. (C) 2000 Cancer Research Campaign.