title: Influence of laser phototherapy (λ660 nm) on the outcome of oral chemical carcinogenesis on the hamster cheek pouch model: histological study.
abstract: OBJECTIVE
  This study aimed to evaluate, histologically, the effect of low-level laser therapy (LLLT) (λ660 nm) on DMBA chemically induced lesions of the oral mucosa of hamsters.
  
  
  BACKGROUND
  Squamous cell carcinoma (SCC) is the most common neoplasm of the oral cavity. It is aggressive, highly proliferative, invasive, and metastatic. There is evidence that LLLT similarly affects neoplasic and non-neoplasic cells.
  
  
  METHODS
  Cancerous lesions were induced on the cheek pouch of 15 golden Syrian hamsters by using DMBA 3 times a week for 8 weeks. At the end of the cancer induction (8 weeks), animals in G1 were killed and the presence of tumors confirmed. Animals in G3 were irradiated (λ660 nm, 30 mW, CW, Ø=3 mm, area: 0.07 cm(2), 424 mW/cm(2), 133 sec, 56.4(2)J/ cm(2), 4J) at every other day for 4 weeks. G2 received no interventions for the same period. Samples were taken and underwent histological analysis by light microscopy.
  
  
  RESULTS
  GI showed 100% well-differentiated SCC. G2 showed 20% moderately differentiated and 80% well-differentiated SCC. G3 showed 40% well-differentiated, 40% poorly differentiated, and 20% moderately differentiated SCC. Significant differences (p=0.02) in the amount of well-differentiated SCC were seen between G1 and G3 and between G3 and G2 (p=0.04). Significant difference was also seen between G3 and G1 and G2 with regard to the amount of poorly differentiated tumors (p=0.04).
  
  
  CONCLUSIONS
  It is concluded that LLLT, within the parameters used in the present study, caused a significant progression of the severity of SCC in the oral cavity of hamsters.
authors: Center of Biophotonics, School of Dentistry, Federal University of Bahia, Salvador, Brazil.
authors: Juliana S
authors: JS
authors: de C Monteiro
authors: Ant Nio Luiz Barbosa
authors: AN
authors: Pinheiro
authors: Susana C P S
authors: SC
authors: de Oliveira
authors: Gilberth T S
authors: GT
authors: Aciole
authors: Jos A C
authors: JA
authors: Sousa
authors: Maria C T
authors: MC
authors: Canguss
authors: Jean Nunes
authors: JN
authors: Dos Santos
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000737:chemistry / Q000473:pathology*; D002610:Cheek; D006224:Cricetinae; D018450:Disease Progression; D006258:Head and Neck Neoplasms / Q000737:chemistry / Q000473:pathology*; D028022:Low-Level Light Therapy / Q000009:adverse effects*; D008297:Male; D008647:Mesocricetus; D009061:Mouth Mucosa; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000473:pathology*; D000077195:Squamous Cell Carcinoma of Head and Neck
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene