BACKGROUND: Topical photodynamic therapy (PDT) for actinic keratoses (AK) is hampered by pain during illumination and inferior efficacy in organ-transplant recipients (OTR).

OBJECTIVES: We assessed ablative fractional laser (AFL)-assisted daylight photodynamic therapy (PDT) (AFL-dPDT) compared with daylight PDT (dPDT), conventional PDT (cPDT) and AFL alone (AFL) in field treatment of AK in OTR.

METHODS: In each patient, four areas in the same region were randomized to one treatment with AFL-dPDT, dPDT, cPDT and AFL. AFL was delivered with a 2940-nm AFL at 2·3 mJ per pulse, 1·15 W, two stacks, 50-μs pulse-duration, 2·4% density. In dPDT and AFL-dPDT, methyl aminolaevulinate (MAL) was applied for 2·5 h without occlusion during daylight exposure. For cPDT, MAL was occluded for 3 h followed by red-light (630 nm) irradiation at 37 J cm(-2). The primary end-point was complete response (CR) 3 months post-treatment.

RESULTS: Sixteen patients with 542 AK (grades I-III) in field-cancerized skin of the scalp, chest and extremities were treated during August and September 2012. After 3 months, CR (AK I-III) rates were 74% after AFL-dPDT, 46% after dPDT, 50% after cPDT and 5% after AFL (P < 0·001). CR rates in AFL-dPDT, dPDT and cPDT were also significantly different (P = 0·004). Median maximal pain scores differed significantly during AFL-dPDT (0), dPDT (0), AFL (0) and cPDT (5) (P < 0·001). Erythema and crusting were more intense following AFL-dPDT than dPDT and cPDT, but only transient hypopigmentation was observed.

CONCLUSIONS: AFL-dPDT is a novel PDT modality that enhances CR with excellent tolerability compared with dPDT and cPDT in difficult-to-treat AK in OTR.