Topical 5-aminolevulinic acid mediated photodynamic therapy of superficial basal cell carcinoma using two light fractions with a two-hour interval: long-term follow-up

Abstract

Photodynamic therapy (PDT) of superficial basal cell carcinoma using topical 5-aminolaevulinic acid (ALA) and 75-100 J/cm2 light dose yields unsatisfactory long-term results. In several animal models, illumination with two light fractions approximately 2 h apart was considerably more effective than single illumination, suggesting the need for a pilot clinical study. Fifteen patients with a total of 86 primary superficial basal cell carcinomas, received topical ALA and were illuminated 4 and 6 h later, both with 45 J/cm2 laser light (633+/-1 nm). Fluorescence spectra were measured before and immediately after each illumination. At a mean follow-up of 59 months (range 44-82), 67 lesions could be evaluated, 56 of which showed a complete response (84%). Cosmesis was good/excellent in 88% of the complete response group and fair in 12%. There was no correlation between protoporphyrin fluorescence and response, but a significant correlation between the percentage of fluorescence left after photobleaching by the first illumination and the amount of protoporphyrin re-synthesized 2 h later. In conclusion, the long-term complete remission rate of fractionated ALA-mediated PDT of superficial basal cell carcinoma as reported here is significantly better than after PDT with single illumination previously reported by others, but equal to studies using single illumination with a much higher light fluence. Further improvement may be possible by reducing the fluence of the first fraction, with constant total fluence.