LONG-TERM FOLLOW-UP AND HISTOLOGICAL-CHANGES OF SUPERFICIAL NONMELANOMA SKIN CANCERS TREATED WITH TOPICAL DELTA-AMINOLEVULINIC-ACID PHOTODYNAMIC THERAPY

Objective: To investigate the immediate and longterm effects of photod ynamic therapy with delta-aminolevulinic acid (ALA-PDT) on superficial basal cell carcinomas (BCC) and superficial squamous cell carcinomas (SCC). Design: Retrospective study with 60 months of maximal follow-up . Setting: University-based hospital in Graz, Austria. Patients: Forty -seven subjects with a total of 95 superficial BCC and 35 superficial SCC. Interventions: A compound of 20% delta-aminolevulinic acid was to pically applied under an occlusive and light-shielding dressing before exposure to either UV-A or different wave bands of polychromatic visi ble light (full-spectrum visible light, >515, >570, or >610 nm). Main Outcome Measures: Primary tumor responses and recurrence rates in the long-term follow-up, as well as histological changes associated with A LA-PDT, were studied. Results: The complete primary response rate for all wave bands of light was 86% (82/95) for superficial BCC and 54% (1 9/35) for superficial SCC. There was no statistically significant diff erence among the response rates to the different wave bands of light. After a median follow-up of 19 months (range, 3-60 months) for BCC and 8 months (range, 3-47 months) for SCC, the overall recurrence rate wa s 44% (36/81) and 69% (11/16), respectively. At 36 months after therap y, the projected disease-free rate was 50% (95% confidence interval, 4 3%-57%) for BCC vs 8% (95% confidence interval, 7%-9%) for SCC (P<.001 , log-rank test). Histopathologic studies revealed a significant incre ase of fibrosis in the dermis after ALA-PDT and appearance of a sharp border between fibrotic and nonfibrotic tissue. In 15 of 16 BCC examin ed, the border between fibrotic and nonfibrotic tissue was deeper in t he dermis than the maximum tumor thickness before therapy (P<.001,Wilc oxon signed rank test). Similar histopathologic observations were made in SCC. Conclusions: Our study revealed poor long-term cure rates for superficial BCC and SCC treated with topical ALA-PDT and visible ligh t. The histopathologic observations showing remarkable fibrosis in the dermis indicated that the effect of AW-PDT reached deeper than the in itial depth of invasiveness of the neoplastic tissue, suggesting in tu rn that the poor long-term results of ALA-PDT cannot be explained by i nsufficient penetration of the therapy effect.