A randomized split-scalp study comparing calcipotriol-assisted methyl aminolaevulinate photodynamic therapy (MAL-PDT) with conventional MAL-PDT for the treatment of actinic keratosis

Abstract

Background Topical photodynamic therapy (PDT) is an approved treatment for actinic keratosis (AK). To enhance the efficacy of PDT for AKs, physical and chemical pretreatments have been suggested. ObjectivesMethodsTo compare the efficacy and safety of the combination of topical calcipotriol (CAL) before methyl aminolaevulinate (MAL)-PDT for AKs of the scalp vs. conventional MAL-PDT in a randomized controlled clinical trial. Twenty patients with multiple AKs on the scalp were randomized to receive conventional MAL-PDT with previous curettage on one side of the scalp and CAL-assisted MAL-PDT once a day for 15 days before illumination on the other side. After 3 months, patients were evaluated for clearance of AKs, side-effects and histopathology before and after the procedure. Protoporphyrin IX (PpIX) fluorescence was measured before and after illumination on both sides. ResultsConclusionsAll 20 patients completed the study. Overall AK clearance rates were 921% and 820% for CAL-PDT and conventional PDT, respectively (P < 0001). Grade 1 AKs showed similar response rates for both sides (P = 0055). However, grade II AKs showed more improvement on the CAL-PDT side (90%) than on the MAL-PDT side (63%) (P < 0001). Before illumination, PpIX fluorescence intensity was higher on the CAL-assisted side (P = 0048). The treatment was more painful on the CAL-PDT side, although well tolerated. The mean visual analogue scale score was 54 14 on the CAL-PDT side and 40 069 on the conventional MAL-PDT side (P = 0001). Side-effects such as erythema (P = 0019), oedema (P = 0002) and crusts (P < 0001) were more pronounced on the CAL-assisted side. Histopathological analyses were obtained from five patients and both sides showed improved keratinocyte atypia following PDT, with slightly more improvement on the CAL-assisted side. CAL-assisted PDT proved to be safe and more effective than conventional MAL-PDT for the treatment of AKs on the scalp. CAL pretreatment increased PpIX accumulation within the skin and may have enhanced the efficacy in this first human trial.