Counteracting Side-effects of Photodynamic Therapy for Actinic Keratoses

Actinic keratoses (AKs) are precursors of squamous cell carcinomas and early intervention is important. Photodynamic therapy (PDT) is often first-choice treatment for widespread AKs. Classic PDT consists of: Superficial curettage, application of 5-aminolevulinic acid or methyl aminolevulinate, incubation and protoporphyrin IX (PpIX) accumulation under occlusion for 3 hours, followed by illumination with red light-emitting diode light (37 J/cm²). Classic PDT is effective in treating AKs, but side-effects include unpleasant pretreatment, severe pain during illumination, inflammation after treatment, and long waiting time in the clinic.

This targeted mini review describes efforts to counteract side-effects and simplify the procedure considering the clinic capacity. Changes are only acceptable if treatment effect is maintained.

We introduce the following procedure changes: (i) reducing pre-treatment pain, bleeding, and oozing by omitting curettage; (ii) long-term illumination for 2 hours during PpIX formation (already in use as daylight PDT) and shortening of incubation time from 3 hours to 30 minutes to minimize pain and inflammation risk. In addition, options of timing, incubation, and illumination indoors and outdoors are discussed, focusing on advantages and disadvantages for patients and clinics.

We report several options to counteract side-effects of classic PDT.