Optimization of treatment parameters for Foscan-PDT of basal cell carcinomas

BACKGROUND AND OBJECTIVE: Basal cell carcinomas (BCCs) are the most common form of skin cancers with high and increasing incidence rates. Photodynamic therapy (PDT) with mTHPC (Foscan) has shown to be a promising treatment alternative with good cosmetic results. The current study was aimed to determine optimal treatment parameters for this indication.

STUDY DESIGN/MATERIALS AND METHODS: mTHPC-PDT was performed in 117 patients with a total of 460 BCCs with diagnosis confirmed by scratch cytology. Treatment parameters were altered as follows: Foscan dose 0.03-0.15 mg/kg, drug-light interval (DLI) 1-96 hours, total energy density 20-120 J/cm(2). Outcomes were assessed 8 weeks post-PDT following WHO guidelines.

RESULTS: The overall rate of complete remissions (CR) was 96.7% and the cosmetic outcome was very good. In the largest subgroup (n=80) where low-dose Foscan was applied (0.05 mg/kg mTHPC; 48 hours DLI; 50 J/cm(2) total energy density), a CR rate of 100% with a high and narrow 95% Confidence Interval of 0.955-1.000 was achieved. Smaller variations of the treatment parameters (i.e., reducing the photosensitizer dose to 0.04 mg/kg or shortening the DLI to 24 hours) yielded similarly good results. Side effects were encountered in 52 out of 133 PDT sessions. They were more common in patients who had received high drug doses (0.06-0.15 mg/kg) and comprised mostly pain and phototoxic reactions. Three patients developed severe sunburns with subsequent scarring at the injection site following bright sunlight exposure 15-19 days after photosensitizer administration.

CONCLUSIONS: The presented data suggest that mTHPC-PDT with the treatment parameters mentioned above seems to be an effective treatment option for BCCs. If sensibly applied, it is well tolerated and provides mostly excellent cosmetic results. Long-term results are yet to be evaluated.