Photodynamic therapy for facial squamous cell carcinoma in cats using Photofrin®

Background: Photodynamic therapy (PDT) has been shown to be an effective treatment modality for surface-oriented neoplasms of the skin, respiratory, gastrointestinal and urogenital systems. The purpose of our study was to assess the safety and efficacy of PDT using Photofrin® in the treatment of squamous cell carcinomas of feline facial skin. Materials and Methods: Cats with naturally occurring squamous cell carcinomas of the skin were entered into the study. PDT was delivered to the tumors using an argon-pumped dye laser 48 hours after the administration of the photosensitizer porfimer sodium (Photofrin®). Following treatment, the tumors were evaluated for complete response rates and local control durations. Results: Eight tumors were staged T1a, 9 staged T1b, and 14 staged T2b. Complete response rates as well as local control durations were significantly related to stage (p < 0.0001). Complete response was achieved in 100% of the T1a tumors and 53% of the T1b tumors; the overall 1-year local control rate for all treated tumors was 62%. Clinical, hematological, and biochemical evidence of toxicity was not seen in any cat following drug administration. Conclusion: PDT with the photosensitizer Photofrin® was safe and effective in treating early stage squamous cell carcinomas of the feline skin.