• actinic keratoses;
  • cryotherapy;
  • methyl aminolaevulinate;
  • photodynamic therapy;
  • randomized controlled trial


Background  Actinic keratosis (AK), the most common premalignant skin condition, can represent a management challenge. Treatment should not only be effective, but also well tolerated and allow for good cosmesis on typical sun-exposed highly visible body sites.

Objectives  The primary objective was to compare the lesion response and subject preference for topical methyl aminolaevulinate (MAL)-photodynamic therapy (PDT) vs. cryotherapy for the treatment of AK.

Methods  In this 24-week, multicentre, randomized, intraindividual (right–left) study, subjects received both one treatment session of MAL-PDT and a double freeze–thaw cryotherapy; the treatments were randomly allocated to either side of the face/scalp. Lesions with a noncomplete response were retreated after 12 weeks. The primary assessments were the subject's overall preference and lesion response at week 24. Secondary assessments included lesion response at week 12, cosmetic outcome, subject and investigator cosmetic outcome preference at week 24, and investigator overall preference at week 24. Skin discomfort and adverse events were also evaluated.

Results  In total, 119 subjects with 1501 lesions were included in the study. At week 12, treatment with MAL-PDT resulted in a significantly larger rate of cured lesions relative to cryotherapy (percentage lesion reduction from baseline: 86·9% vs. 76·2%; P < 0·001). At week 24, both treatment groups showed a high rate of cured lesions (89·1% for MAL-PDT vs. 86·1% for cryotherapy; P = 0·20; 95% confidence interval: −1·62 to 7·67). Results for subject and investigator preferences as well as cosmetic outcome favoured MAL-PDT. Both treatment regimens were safe and well tolerated.

Conclusions  The present study shows that, when treated with both MAL-PDT and cryotherapy, subjects significantly prefer MAL-PDT treatment for AK. MAL-PDT is an attractive treatment option for AK, with comparable efficacy and superior cosmetic outcomes compared with double freeze–thaw cryotherapy.