Background: Photodynamic therapy (PDT) has been shown to be an effective treatment modality for surface-oriented neoplasms of skin, respiratory, gastrointestinal, and urogenital systems. The purpose of our study was to assess the safety and efficacy of PDT using PhotofrinR in the treatment of squamous cell carcinomas of feline face 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 (PhotofrinR). Following treatment, tumors were evaluated for complete response rates and local control durations.

Results: Eight tumors were staged T1a, 9 T1b, and 14 T2b. Complete response rates as well as local control durations were significantly (P < 0.0001) related to stage. Complete response was achieved in 100% for the T1a tumors and 53% for the T1b tumors; 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 PhotofrinR was safe and effective in treating early stage squamous cell carcinomas of the feline skin.(Chang Gung Med J 1998;21:13-9)

Key words: photodynamic therapy, photosensitizer, PhotofrinR, squamous cell carcinoma.

Received: Jun, 25, 1997; Accepted: Nov. 20,1997.

Address for reprints: Dr.Chang-Jen Chabg , Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital. 199, Tung-Hwa North Road, Taipei, Taiwan, R.O.C. tel:886-2-27135211 ext.3502; Fax:886-2-25140600