title: Temperature-Modulated Photodynamic Therapy for the Treatment of Actinic Keratosis on the Extremities: A One-Year Follow-up Study.
abstract: BACKGROUND
  The efficacy of photodynamic therapy (PDT) using topical 5-aminolevulinic acid (ALA) for the treatment of actinic keratosis (AK) is lower on the distal extremities compared with head and neck areas. A recent pilot study demonstrated increased efficacy of ALA PDT when the skin is warmed during ALA incubation. Prolonged clearance rates on the heated extremity were noted in 3 subjects that were evaluated after the study ended. The aim of this study was to evaluate the longevity of clearance rates after temperature-modulated PDT for the treatment of AKs on the extremities.
  
  
  METHODS
  A total of 18 subjects (20 pairs of extremities) with at least 10 AKs on the upper or lower extremities were enrolled in the single-center study. Twenty percent ALA was applied to both extremities and heated during the 1-hour incubation period, followed by exposure to 10 J/cm 417-nm blue light. Lesions were photographed, counted, and templated at baseline, 1 week, and 3, 6, 9, and 12 months after treatment.
  
  
  RESULTS
  A total of 17 subjects completed the 1-year study. The total number of lesions counted at baseline was 724 Grade 1 and 2 AKs (median 15 on each extremity). The lesion count at 3 and 12 months was 70 (9.6%) and 72 (9.9%), respectively. Grade 3 AKs did not resolve with treatment. The median baseline temperature of the treated extremities was 31.6°C. The median maximum temperature during the 1-hour incubation period was 41.2°C. The median clearance at 3 months was 90% and the same was maintained at 12 months. No new AK lesions formed in the treated areas within the 12-month follow-up period.
  
  
  CONCLUSIONS
  Warming the skin after application of ALA is well tolerated, does not increase side effects, and increases the long-term efficacy of PDT for the treatment of AKs. The authors suggest that mild skin warming may both improve efficacy and reduce variability of response to PDT in practice.
authors.affiliation: *Andrea Willey, MD, Surgical & Aesthetic Dermatology Sacramento, Sacramento, California; †Department of Dermatology, University of California Davis, Sacramento, California; ‡Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts; §Harvard Medical School, Boston, Massachusetts.
authors.forename: Andrea
authors.initials: A
authors.lastname: Willey
authors.forename: R Rox
authors.initials: RR
authors.lastname: Anderson
authors.forename: Fernanda H
authors.initials: FH
authors.lastname: Sakamoto
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000622:Aminolevulinic Acid / Q000008:administration & dosage; D005260:Female; D005500:Follow-Up Studies; D005542:Forearm; D006801:Humans; D006979:Hyperthermia, Induced; D055623:Keratosis, Actinic / Q000188:drug therapy* / Q000473:pathology; D007866:Leg; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy / Q000009:adverse effects / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D013696:Temperature; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid