title: Photodynamic therapy for Bowen's disease and squamous cell carcinoma of the skin.
abstract: BACKGROUND
  Photodynamic therapy involves the activation by visible light of a previously administered photosensitizing agent in order to cause tumor necrosis. Skin tumors can be treated with topical photosensitizers and thus avoiding systemic side effects. In this study we evaluate the immediate and long-term effects of photodynamic therapy (PDT), using aminolevulinic acid (ALA) as a photosensitizer and a non-laser light source, on Bowen's disease (intra-epithelial squamous cell carcinoma) and on frank squamous cell carcinoma (SCC) of the skin.
  
  
  METHODS
  ALA in cream form (20%) was topically applied on biopsy-proven Bowen's disease or SCC of the skin. The lesions were covered with occlusive and light-shielding dressing. Sixteen hours later, they were submitted to a 10-min light session using Versa-Light™, a non-laser light source (spectral output of 580-720nm and 1250-1600nm, 100J/cm(2)). The initial evaluation was done 21 days post-treatment and every 3m thereafter. Patients that did not respond to treatment after two to three sessions were referred to surgery.
  
  
  RESULTS
  Forty Bowen's disease lesions (24 patients) and 43 SCC lesions (18 patients) underwent treatment. Median follow-up was 21±8m. No patient had any remarkable side effects. Thirty-four Bowen's disease (85%) lesions completely responded as did 32 SCC lesions (74%).
  
  
  CONCLUSIONS
  Our findings showed that PDT is highly effective in treating Bowen's disease and SCC lesions and can be used as a first treatment modality in so far as its use does not preclude the subsequent surgery recommended for the small percentage of failures.
authors.affiliation: Department of Surgery "A", Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Riad
authors.initials: R
authors.lastname: Haddad
authors.affiliation: Department of Plastic Surgery, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Eviatar
authors.initials: E
authors.lastname: Nesher
authors.affiliation: Department of Plastic Surgery, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Jerry
authors.initials: J
authors.lastname: Weiss
authors.affiliation: Department of Surgery "A", Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Skornick
authors.affiliation: Department of Surgery "A", Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Hanoch
authors.initials: H
authors.lastname: Kashtan