Simulated Daylight Photodynamic Therapy for Superficial Basal Cell Carcinoma and Actinic Keratoses

Abstract

The overall aim of this thesis was to evaluate simulated daylight photodynamic therapy (SDL-PDT) for the treatment of actinic keratoses (AKs) and superficial basal cell carcinoma (sBCC). The included studies assessed this novel lighting system from multiple perspectives. A technical validation study determined whether the light intensity achieved with SDL-PDT met theoretical treatment requirements. Additionally, two randomized controlled trials (RCTs) compared the effectiveness of SDL-PDT and C-PDT in the treatment of sBCC and mild to moderate AKs. Finally, a qualitative study explored patients’ experiences with the two treatment methods.

Paper I presents the results of the technical validation study, in which the illuminance of SDL-PDT was evaluated at different angles and distances relative to the light sources. The findings underscore the importance of correct patient positioning, with optimal illumination achieved at angles of 0°-45°, while 90° angles resulted in inadequate exposure. Papers II and III report the outcomes of two RCTs comparing SDL-PDT and conventional PDT (C-PDT) for sBCC and AKs, respectively. After one year, clearance rates were significantly higher with C-PDT for both sBCC (91.8% vs. 62.4%) and AKs (85.3% vs. 71.0%). Paper IV presents a qualitative interview study conducted four weeks post-treatment with participants from the AK trial. The study revealed that while C-PDT caused severe pain and prolonged post-treatment reactions impacting daily life, SDL-PDT was associated with only mild discomfort and skin reactions. Most participants preferred SDL-PDT over C-PDT, although concerns about its long-term effectiveness were also expressed.

This thesis highlights the importance of optimal patient positioning for effective SDL-PDT treatment and emphasizes the need to balance treatment effectiveness with patient experience. While SDL-PDT offers a less painful alternative, its effectiveness is lower than that of C-PDT for treating sBCC and mild to moderate AKs.