For patients with high-grade actinic keratosis lesions, ablative fractional laser (AFL)-assisted photodynamic therapy (PDT) with the use of high laser depth parameters is recommended, according to the results of a single-blinded, randomized, comparative, prospective study (ClinicalTrials.gov identifier: NCT03325803). Findings from the analysis were published in the Journal of the American Academy of Dermatology.

Investigators sought to explore whether increased laser ablative depth affects the efficacy, cosmetic outcomes, adverse effects, and protoporphyrin IX (PPIX) accumulation of AFL-PDT among patients with facial actinic keratosis. Overall thickness of the lesions was classified as grades I through III.

Patients with an indication for PDT were randomly assigned to treatment with AFL-PDT, using 150, 350, or 500 µm of ablative depth therapy, all with the same coagulation level and treatment density (coagulation, level 1; treatment density, 22%; single pulse). Irradiation at a dose of 37 J/cm2, using a red light-emitting diode lamp, followed the application of topical methyl aminolevulinate. The primary study outcomes were complete response rates at 3 and 12 months posttreatment. Levels of accumulated PPIX were used to assess fluorescence intensity measurements.

Overall, 60 participants with a total of 366 actinic keratosis lesions were randomly assigned to 1 of 3 treatment groups: 20 patients in the 150 µm-AFL-PDT group, 19 patients in the 350 µm-AFL-PDT group, and 21 patients in the 500 µm-AFL-PDT group. No differences were observed in the 3 groups with respect to age, sex, Fitzpatrick score, or Olsen grade.

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In those with Olsen grade I or II lesions, no differences were reported among the 3 groups with respect to complete response. In contrast, in participants with Olsen grade III lesions, complete response rates were significantly better in the 500 µm-AFL-PDT group (87.2% at 3 months; 79.5% at 12 months) compared with the 150 µm-AFL-PDT group (68.4% at 3 months; 57.9% at 12 months; P <.05).

No significant differences were observed among the groups in terms of PPIX accumulation, treatment safety, or cosmetic outcomes.

One major limitation of the current study was the small sample size. Moreover, the use of noninvasive surface fluorescence photography to measure PPIX accumulation at the skin surface did not permit quantification of PPIX accumulation in deeper layers of the skin. The investigators concluded that AFL-assisted PDT with higher laser depth parameters has demonstrated efficacy for the pretreatment of actinic keratosis lesions.

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Reference

Seo J-W, Kim H-J, Song K-H. A comparison of the efficacy of ablative fractional laser assisted photodynamic therapy according to ablative depth for actinic keratosis: a single-blinded, randomized, comparative, prospective study [published online January 25, 2019]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2019.01.033.