Photodynamic therapy of feline superficial squamous cell carcinoma using topical 5-aminolaevulinic acid

A study was undertaken to investigate the treatment of superficial squamous cell carcinoma of the nasal planum, pinna and eyelid in cats by photodynam ic therapy, using topical Ei-aminolaevulinic acid cream, with subsequent ex posure to red light of wavelength 635 nm, supplied by a light-emitting diod e source. A total of 13 squamous cell carcinomas were treated, including 10 nasal planum lesions, two pinnal lesions and one eyelid lesion. After a si ngle treatment, complete responses were seen in nine out of 10 nasal planum lesions, one out of two pinnal lesions and the eyelid lesion. The overall complete response rate for lesions managed with a single photodynamic thera py treatment was 85 per cent. Seven of the 11 lesions (63.6 per cent) showi ng a complete response subsequently recurred; the time to recurrence ranged from 19 to 56 weeks (median 21 weeks, mean 26.7 weeks).