Efficacy of low-dose mTHPC-PDT for the treatment of basal cell carcinomas

Objectives: Basal cell carcinomas (BCCs) are the most common skin cancers, and incidence rates are still rising. Photodynamic Therapy (PDT) with mTHPC (Foscan (R)) has shown to be a promising alternative to other treatments with good cosmetic results. This study was performed to determine optimal treatment parameters for this indication. Methods: 117 patients with a total of 460 BCCs received mTHPC-PDT. The treatment parameters were varied as follows: Foscan (R) dose 0.03 - 0.15 mg/kg, drug-light interval (DLI) 1 - 96 hours, total energy density 20 -120 J/cm2. The clinical outcomes were assessed 8 weeks after PDT following WHO guidelines. Results: The rate of complete remissions (CR) was 96.7% and the general cosmetic outcome rated very good. In the largest subgroup (n=80) with low-dose mTHPC (0.05 mg/kg mTHPC; 48 hours DLI; 50 J/cm2 total energy density), a CR rate of 100% was accomplished. Minor changes of the parameters (0.04 mg/kg mTHPC or 24 hours DLI) yielded similar 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 pain and phototoxic reactions. 3 patients developed severe sunburns with subsequent scarring at the injection site following sunlight exposure 2-3 weeks after mTHPC administration. Conclusions: The data suggests that low-dose mTHPC-PDT is an effective treatment option for BCCs. If sensibly applied, it is well tolerated and provides mostly excellent cosmetic results. The evaluation of long term results is still to be undertaken.