[Potassium hydroxide 5 % solution in actinic keratosis : A novel therapeutic approach in the lesion-directed...

Actinic keratosis (AK) is an epithelial carcinoma in situ of the skin. There is a need for early treatment due to the risk of malignant transformation. In addition to being effective, the initial therapy in particular should be well tolerated and user-friendly. Potassium hydroxide (KOH) solution is already established as keratolytic treatment option for hyperkeratotic skin diseases such as mollusca contagiosa.

A prospective single-arm, multicentre medical device study (Treatment of AK with KOH, TAKKOH) was conducted to investigate the efficacy and safety of KOH 5% solution for the treatment of mild to moderate AK. Patients applied KOH solution twice daily for 14 days with a subsequent off-treatment phase of 14 days (≙ one treatment cycle) for a maximum of three treatment cycles or at least until treatment success was achieved. Treatment success, defined as complete remission (CR) of all AK lesions of a patient, was the primary objective. Secondary objectives included the evaluation of partial remission (PR), the number of AK lesions in remission, efficacy assessment by investigators and patients with a 6‑point grading system and several safety parameters.

In all, 73 patients were enrolled in the study. CR was achieved in 54.9% of patients, whereas PR was observed in 64.8% with a 69.9% reduction in lesion numbers. With respect to safety, 46.6% of the patients experienced adverse events. Most of these events (82.6%) were adverse reactions comprising exclusively short-lived and mild local skin reactions.

The study provides an indication of the efficacy and safety of KOH 5% solution for the lesion-directed topical therapy of AK.