Methyl aminolaevulinate-photodynamic therapy: a review of clinical trials in the treatment of actinic keratoses and nonmelanoma skin cancer

Methyl aminolaevulinate-photodynamic therapy (MAL-PDT) has advanced the management of nonmelanoma skin cancer (NMSC), providing a treatment option for actinic keratosis (AK), basal cell carcinoma [both superficial (sBCC) and nodular (nBCC)] and Bowen's disease, with good clinical outcomes, low recurrence rates and enhanced cosmetic acceptability. Excellent results have been reported, with complete responses (CRs) in AK ranging from 69% to 93% at 3 months; CRs in Bowen's disease are 93% at 3 months and 68% at 24 months. In sBCC, CRs range from 85% to 93% at 3 months and are comparable with cryosurgery up to 60 months (75% vs. 74%). In nBCC, CRs range from 75-82% at 3 months to 77% at 60 months. MAL-PDT specifically targets diseased cells, leaving healthy tissue unharmed. This noninvasive treatment option is associated with minimal risk of scarring. Moreover, systemic uptake of MAL is negligible and the local phototoxic reactions that often occur during treatment rapidly heal to produce excellent cosmetic results. The side-effects of therapy, which are predominantly local phototoxic effects (burning, stinging and prickling sensations), are of mild-to-moderate intensity, of short duration and easily managed. Overall, the efficacy and low risk of side-effects afforded by this therapy have resulted in high patient preference in clinical trials. The current evidence base for MAL-PDT in the treatment of AK and NMSC is reviewed in this article.