| Co-Investigator(Kenkyū-buntansha) |
OHSHIRO Kazufumi Niigata University, Graduate School of Medical and Dental Sciences, Assistant, 大学院・医歯学総合研究科, 助手 (50332648)
SUZUKI Makoto Niigata University, Medical and Dental Hospital, Lecture, 医歯学総合病院, 講師 (50107778)
SAKU Takashi Niigata University, Graduate School of Medical and Dental Sciences, Professor, 大学院・医歯学総合研究科, 教授 (40145264)
MIYAZAKI Hideo Niigata University, Graduate School of Medical and Dental Sciences, Professor, 大学院・医歯学総合研究科, 教授 (00157629)
IDA Hiroko Niigata University, Graduate School of Medical and Dental Sciences, Assistant, 大学院・医歯学総合研究科, 助手 (60293213)
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| Research Abstract |
Oral cancers and precancerous lesions were collected from China, Sri-Lanka, Bangladesh, and India. Among the present collection of oral cancers and precancerous lesions, we found lesions which can be referred to as superficial carcinoma in many areas with or without the custom of chewing tobacco. There were 128 cases of superficial carcinoma among 800 cases of oral squamous cell carcinoma. Among them, 82 superficial carcinomas out of 680 cases from the Japanese population. The clinicopathobgical characteristics of the Japanese patients with superficial carcinoma were as follows : the patients were mainly older women ; the superficial carcinoma arose more commonly in the longue, gingival, and buccal mucosa ; the Lesions were multiple and recurrent ; less consumptions of tobacco for smoking and alcohol than patients with invasive carcinomas ; the superficial carcinoma lesions had some association with the patients' anamneses for prosthetic treatments. In contrast, the lesion from Asian c
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ountries was found exclusively in the buccal mucosa and gingival, and the patients were mainly males with chewing habits. Histopathobgy of the superficial carcinoma was the same among the Japanese and Asian patients. They were commonly composed of carcinoma in-situ, which could be divided into three types, such as basaloid, verrucous, and acanthotic, and of surrounding epithelial dysplasia with the characteristic two-phase appearances. In order to recognize such a disease entity of superficial carcinoma of the oral mucosa, a workshop was taken place in Singapore in August 2002, at which oral pathologists from Japan, Korea, Malaysia, Indonesia, Sri-Lanka, and the United Kingdom attended and discussed about the possibility of the concept
Using paraffin-embedded specimens collected from Asian countries, superficial carcinomas were investigated in several aspects as follows : the characteristic two-phase appearance in epithelial dysplasia was investigated by immunohistochemistry and in-situ hybridization, and its molecular mechanism was revealed to be due to apoptosis of prickle cells by mechanical stress of basaloid cell proliferation in the lower layer and thick keratinization in the surface layer. In addition, extracellular matrix remodeling in oral submucous fibrosis was determined for one of the backgrounds of oral carcinogenesis. DNA samples obtained by microdissection were analyzed for mutational events in cancer-related genes. Among them, there were several characteristic mutations in the p53 gene which were shared by the collected cases.
Based on the data obtained in this study, it is highly suggested that superficial carcinomas of the oral mucosa caused by different environmental factors shared similar genetic alterations in the cancer-related genes. Less
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