Thermal Photodynamic Therapy for Actinic Keratoses on Facial Skin: A Proof-of-Concept Study

Warming the skin during the incubation of 5-aminolevulinic acid (ALA) has the potential to improve the efficacy and efficiency of cutaneous photodynamic therapy (PDT) through multiple mechanisms. The aim of this proof-of-concept study is to investigate the efficacy and tolerability of thermal PDT on facial skin and evaluate porphyrin production objectively during the warming period.

Facial skin of 10 subjects was heated during a 20-minute incubation with ALA followed by 10 J/cm blue light illumination. Lesion counts were performed at baseline and 2 months. Porphyrin images were captured and the intensity of fluorescence was measured. The mean intensity of fluorescence after incubation with ALA was compared with baseline.

Ten subjects with 363 actinic keratoses completed the study. The average temperature during incubation with the warming mask was 38 to 42°C. Porphyrin intensity increased significantly after the incubation period (p = .001). The average lesion clearance rate was 91.48%. Five subjects had complete lesion clearance (50%).

This small proof-of-concept study shows that warming facial skin within the range of physiologic tolerability during the incubation of ALA is well tolerated by patients and that porphyrins are efficiently and effectively produced during this defined time and temperature range.