title: Hyperthermia enhances the antitumor effect of photodynamic therapy with ALA hexyl ester in a squamous cell carcinoma tumor model.
abstract: BACKGROUND
  Photodynamic therapy (PDT) using 5-aminolevulinic acid is considered to be ineffective in the treatment of tumors with progression to the deep layer. Therefore, for such tumors, a method is required which can enhance the effectiveness of this therapy. We examined the anti tumor effect of the combination of PDT with 5-aminolevulinic acid hexyl ester (hALA) and hyperthermia (HT) in a squamous cell carcinoma (SCC) tumor model.
  
  
  METHODS
  A tumor model was prepared by subcutaneously implanting SCC into nude mice, and treated with HT, PDT with hALA (hALA-PDT), or hALA-PDT combined with HT (PDT+HT). The treatment was performed by remodeled near infra-red irradiator which allows the generation of two types of rays for PDT and HT. With HT, the tumor was irradiated for raising the temperature with a light dose of 437.5 J/cm(2). With hALA-PDT, the tumor treated with 250 mg/kg hALA was irradiated with a light dose of 50 J/cm(2). With PDT+HT, the tumor was treated as for hALA-PDT except that the temperature was raised during irradiation with a light dose of 437.5 J/cm(2) (including light dose of 50 J/cm(2) for PDT).
  
  
  RESULTS
  The tumor growth rates on Day 12 were 97.10% in HT, 67.55% in hALA-PDT and 33.90% in PDT+HT, and PDT+HT showed significant inhibitory effects on tumor growth, although the anti-tumoral effects of HT and hALA-PDT were not seen.
  
  
  CONCLUSIONS
  hALA-PDT combined with HT demonstrated a significant inhibitory effect on the tumor growth of squamous cell carcinoma showing a progression in the deep layer. This suggests that this therapy is useful for tumors showing progression to the deep layer, which hALA-PDT alone is generally ineffective in treating.
authors.affiliation: Department of Dentistry and Oral Surgery, Mie-chuo Medical Center, National Hospital Organization, 2158-5 Hisaimyojin-cho, Tsu, Mie 514-1101, Japan. shigeaki@clin.medic.mie-u.ac.jp
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Yanase
authors.forename: Jouji
authors.initials: J
authors.lastname: Nomura
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Matsumura
authors.forename: Hideharu
authors.initials: H
authors.lastname: Kato
authors.forename: Toshiro
authors.initials: T
authors.lastname: Tagawa
mesh_terms: D000622:Aminolevulinic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D005260:Female; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods*; D007624:KB Cells; D051379:Mice; D008819:Mice, Nude; D008954:Models, Biological; D018307:Neoplasms, Squamous Cell / Q000188:drug therapy*; D010778:Photochemotherapy / Q000379:methods; D017319:Photosensitizing Agents / Q000494:pharmacology*
chemical_list: D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid; C419924:5-aminolevulinic acid hexyl ester