Patients with actinic keratosis who used UPF 50 sunscreen containing DNA repair enzymes improved significantly more on two measures of malignant progression than did those who used sunscreen alone, according to research published in the Journal of Drugs in Dermatology.
At 6 months, improvements in field cancerization and levels of cyclobutane pyrimidine dimers were significantly greater (P less than .001) for the sunscreen-plus-enzymes group compared with sunscreen-only patients, wrote Dr. Mauro Carducci of Centro Ortopedico di Quadrante in Omegna, Italy, and his associates.
The study is the first of its type to directly compare the clinical effects of two such topicals, the investigators wrote. The findings set the stage for longer, larger trials that are powered to assess the risk of progression to squamous cell carcinoma, they added.
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For the study, 28 patients with AK were randomly assigned to use SPF 50 sunscreen alone or a formula that contained 1% photolyase from Anacystis nidulans and 1% endonuclease from Micrococcus luteus. Patients applied 2 mg/cm2 of sunscreen to treatment areas that contained 4-10 AKs. They were not allowed to use other topicals during the trial or for 2 weeks beforehand.
All of the patients were white and aged older than 65 years; three-quarters were men. The investigators used fluorescence diagnostics with methylaminolaevulinate to measure field cancerization, and analyzed skin biopsies to quantify CPD levels (J Drugs Dermatol. 2015;14[9]:986-90.).
Hyperkeratosis improved the same amount in both groups at month 6, according to the researchers. But field cancerizations dropped 29% from baseline in the sunscreen-plus-enzymes group, compared with a 10% decrease with sunscreen alone (P less than .0001). Likewise, CPD levels fell 61% from baseline in the sunscreen-plus-enzymes group compared with a 35% drop with sunscreen alone (P less than .0001).
Despite those significant differences, the study was not powered to detect differences in the risk of transformation to SCC, the researchers cautioned.
Biodue S.p.A. provided the methyl aminolevulinate used in the study. Dr. Enzo Emanuele, the study’s senior author, is a major shareholder of Living Research S.A.S., a privately held biomedical research organization that provided funding for the work. The other researchers reported no conflicts of interest.