title: Successful treatment of 7,12-dimethylbenz(a)anthracene-induced hamster buccal pouch precancerous lesions by topical 5-aminolevulinic acid-mediated photodynamic therapy.
abstract: BACKGROUND
  Our previous studies found that topical 5-aminolevulinic acid (ALA)-mediated photodynamic therapy (ALA-PDT) with a light dose of 100 J/cm(2) is very effective for human oral precancerous lesions.
  
  
  METHODS
  In this study, 20 7,12-dimethylbenz(a)anthracene (DMBA)-induced hamster buccal pouch precancerous lesions were treated by topical ALA-PDT with a light dose of either 75 J/cm(2) (n = 10) or 100 J/cm(2) (n = 10) using a 640-nm light-emitting diode (LED) light to test which light dose could achieve a better clinical outcome.
  
  
  RESULTS
  The 10 precancerous lesions treated by 75-J ALA-PDT showed complete response in 8 after an average of 3.4 (range, 2-6) treatments and partial response in 2. The 10 precancerous lesions treated by 100-J ALA-PDT demonstrated complete response in 7 after an average of 4.4 (range, 3-6) treatments and partial response in 3. Fisher exact test showed no significant difference in clinical outcome between these two treatment modalities (p = 1.000). One complete-response precancerous lesion in the 75-J ALA-PDT group recurred at the end of 19-week follow-up and another complete response precancerous lesion in the 100-J ALA-PDT group recurred at the end of 16-week follow-up. Both recurrence lesions were treated by the original topical ALA-PDT regimen and demonstrated complete response after 3 PDT treatments. Furthermore, the 5 partial-response precancerous lesions developed into squamous cell carcinomas after 30-week follow-up.
  
  
  CONCLUSIONS
  Our findings indicate that both the 75-J and 100-J topical ALA-PDT treatment modalities are very effective for DMBA-induced hamster buccal pouch precancerous lesions and no significant difference in clinical outcome between these two treatment modalities.
authors.affiliation: Department of Bioscience Technology, Chung Yuan Christian University, Taoyuan, Taiwan. ivyhsu@cycu.edu.tw
authors.forename: Yih-Chih
authors.initials: YC
authors.lastname: Hsu
authors.forename: Deng-Fu
authors.initials: DF
authors.lastname: Yang
authors.forename: Chun-Pin
authors.initials: CP
authors.lastname: Chiang
authors.forename: Jeng-Woei
authors.initials: JW
authors.lastname: Lee
authors.forename: Meng-Kai
authors.initials: MK
authors.lastname: Tseng
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity; D000622:Aminolevulinic Acid / Q000494:pharmacology*; D000818:Animals; D002610:Cheek / Q000473:pathology; D006224:Cricetinae; D008297:Male; D008647:Mesocricetus; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000188:drug therapy*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011230:Precancerous Conditions / Q000139:chemically induced / Q000188:drug therapy*; D013050:Spectrometry, Fluorescence
chemical_list: D017319:Photosensitizing Agents; D015127:9,10-Dimethyl-1,2-benzanthracene; D000622:Aminolevulinic Acid