Randomized, double-blind, prospective study to compare topical 5-aminolaevulinic acid methylester with topical 5-aminolaevulinic acid photodynamic therapy for extensive scalp actinic keratosis

Background 5-aminolaevlinic acid methylester (MAL) and 5-aminolaevulinic acid (ALA) photodynamic therapy (PDT) are both effective treatment options for actinic keratosis (AK). While MAL is significantly more expensive than ALA, no studies have directly compared their efficacy in the treatment of extensive scalp AK. Objectives To compare the efficacy and adverse effects of MAL-PDT with ALA-PDT in the treatment of scalp AK. Methods Sixteen male patients aged 59-87 years with extensive scalp AK were randomized into a double-blind, split-scalp prospective study. Two treatment fields were defined (right and left frontoparietal scalp) and treated 2 weeks apart. These fields were randomized to receive either MAL or ALA as first or second treatment. MAL cream was applied for 3 h; 20% ALA cream was applied for 5 h. A blinded observer assessed efficacy comparing AK counts before and 1 month after treatment. Pain was assessed using a visual analogue scale at 3, 6, 12 and 16 min. Results Fifteen patients completed treatment to both fields. There was a mean reduction from baseline in AK counts with the use of ALA-PDT of 6.2 +/- 1.9 compared with 5.6 +/- 3.2 with MAL-PDT (P = 0.588). All patients experienced pain which was of greater intensity in the ALA-treated side at all time points: 3 min (P = 0.151), 6 min (P = 0.085), 12 min (P = 0.012) and 16 min (P = 0.029). Similarly, duration of discomfort post-procedure persisted for longer following treatment with ALA when compared with MAL-PDT (P = 0.044). Conclusions This study demonstrates that both ALA-PDT and MAL-PDT result in a significant reduction in scalp AK. There is no significant difference in efficacy. However, ALA-PDT is more painful than MAL-PDT in the treatment of extensive scalp AK.