Nd-YAGレーザーの発癌過程に及ぼす影響について

抄録

Currently, Nd-YAG laser has been applied to the management of oral precancerous lesions, such as leukoplakia. It is not rare, however, that such lesions have ill-defined borders and there is a possibility that morphologically normal tissues adjacent to the lesions have malignant potential. The purpose of this study is to evaluate the effects of Nd-YAG laser on tissues which have malignant potential.
Chemical carcinogen, 0.5% 9, 10 dimethyl-1, 2-benzanthracene acetone solution, was applied to the lateral borders of tongues of golden Syrian hamsters thrice weekly for 12 weeks and precancerous lesions were produced. The animals which had tumors less than 2mm in diameter on their tongues were selected for the experiment. In laser irradiation group, the lesions were excised partially by Nd-YAG laser irradiation. In blade excision group, the lesions were excised partially by biopsy forceps. In no-treatment group, the lesions were untreated. The animals in each group were sacrificed 16 weeks later and the tongues were examined histopathologically. Squamous cell carcinoma appeared in 5.0% (1/20) of the animals in no-treatment group, 28.6% (6/21) in laser irradiation group and 16.7% (4/24) in blade excision group. Histopathologically, there was a characteristic view in laser irradiation group, such as small epithelial tissues seen in the muscle layer, which had no connection with the superficial epithelium. A possibility was suggested that incomplete Nd-YAG laser irradiation on precancerous lesions promotes malignant transformation.