Photodynamic therapy of actinic keratoses with 8% and 16% methyl aminolaevulinate and home-based daylight exposure: a double-blinded randomized clinical trial

Abstract

Photodynamic therapy (PDT) is an effective but time-consuming and often painful treatment for actinic keratosis (AK). Home-based daylight-PDT has the potential to facilitate treatment procedure and to reduce associated pain due to continuous activation of small amounts of porphyrins. Moreover, a reduced methyl aminolaevulinate (MAL) concentration may reduce associated inflammation, making the treatment more tolerable for the patients. To compare response rates and adverse effects after PDT using conventional 16% and 8% MAL with home-based daylight exposure in treatment of AK. Thirty patients with mostly thin-grade AK of the face or scalp were treated with 16% and 8% MAL-PDT in two symmetrical areas after application of sunscreen. Immediately after, patients left the hospital with instructions to spend the remaining day outside at home in daylight. Patients scored pain during treatment and light exposure was monitored with an electronic wristwatch dosimeter. The complete response rate after 3 months was 76.9% for 16% MAL and 79.5% for 8% MAL (P = 0.37). Patients spent a mean of 244 min outdoors and received a mean effective light dose of 30 J cm(-2). Light doses of 8-70 J cm(-2) induced similar response rates (P = 0.25). Patients experienced mild to moderate pain during daylight exposure (mean maximal pain score of 3.7). No differences in pain scores and erythema were seen between the areas treated with 16% MAL and with 8% MAL. Home-based daylight-mediated MAL-PDT was an effective and well-tolerated treatment for AK. No differences in response rates or adverse events were found between the areas treated with 16% MAL and with 8% MAL.