title: Feasibility of daylight-mediated photodynamic therapy for actinic keratosis throughout the year in Central and South America: a meteorological study.
abstract: BACKGROUND
  Daylight-mediated photodynamic therapy (DL-PDT) is an efficacious treatment option for thin actinic keratosis (AK) that offers advantages over conventional PDT in terms of tolerability, treatment duration, and cost. A clinical study conducted in Australia determined the mean irradiance during a 2-hour exposure to be 305.8 W/m(2) (range: 40-585 W/m(2) ). The protoporphyrin IX light dose is influenced by latitude, weather conditions, and time of year. A recent study of meteorological data concluded that DL-PDT can be performed effectively throughout the year in Australia.
  
  
  OBJECTIVE
  Based on the same hypothesis and applying the same methodology, the present study investigated the suitability of daylight to perform DL-PDT in Central and South America.
  
  
  METHODS
  Solar radiation and weather data were gathered and analyzed to assess daylight irradiance (light intensity) throughout a full year across 32 geographical locations in Central and South America.
  
  
  RESULTS
  The minimum average daily solar irradiance reported was above 305.8 W/m(2) in all locations investigated throughout the year. Annual averages of daily irradiance ranged from 578 W/m(2) in Chihuahua, Mexico, to 321 W/m(2) in Puerto Montt, Chile.
  
  
  CONCLUSIONS
  Daylight-mediated PDT for AK can be performed effectively throughout the year in Central and South America given that weather conditions permit a comfortable 2-hour direct exposure to daylight.
authors.affiliation: Department of Dermatology, Hospital das Clínicas, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Beni
authors.initials: B
authors.lastname: Grinblat
authors.affiliation: Department of Dermatology, School of Medicine, Hospital Italiano, Buenos Aires, Argentina.
authors.forename: Gaston
authors.initials: G
authors.lastname: Galimberti
authors.affiliation: Biomer SA, Santiago, Chile.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Pantoja
authors.affiliation: Group of Investigative Dermatology (GRID), School of Medicine, University of Antioquia, Medellín, Colombia.
authors.forename: Gloria
authors.initials: G
authors.lastname: Sanclemente
authors.affiliation: Cirugía Dermatológica y Oncología Cutánea Department, Hospital Militar Dr Carlos Arvelo, Central University of Venezuela, Caracas, Venezuela.
authors.forename: Miguel
authors.initials: M
authors.lastname: Lopez
authors.affiliation: Centro Dermatológico Dr Ladislao de la Pascua, Mexico City, Mexico.
authors.forename: Daniel
authors.initials: D
authors.lastname: Alcala
authors.affiliation: Department of Dermatology, Hospital das Clínicas, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Luís
authors.initials: L
authors.lastname: Torezan
authors.affiliation: Galderma International, Paris, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Kerob
authors.affiliation: Galderma R&D SNC, Sophia Antipolis, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Pascual
authors.affiliation: Centro de Investigaciones Dermatologicas, Hospital General de Agudos "Dr Cosme Argerich", Buenos Aires, Argentina.
authors.forename: Edgardo
authors.initials: E
authors.lastname: Chouela
mesh_terms: D005240:Feasibility Studies; D006801:Humans; D055623:Keratosis, Actinic / Q000188:drug therapy*; D055904:Meteorology / Q000706:statistics & numerical data; D008800:Mexico; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D012621:Seasons; D013020:South America; D013472:Sunlight; D013997:Time Factors; D014887:Weather
chemical_list: D017319:Photosensitizing Agents