| Research Abstract |
The vascular architecture of DMBA (9, 10-dimethyl I, 2-benzanthracene) induced tongue carcinoma in the hamster was examined. Changes in tumor vessels and their significance during growth of invasive oral squamous cell carcinoma was observed. Tongue cancer was induced by abrading the right margin of the tongue of each hamster with an endodontic barbed broach and subsequently applying 1.0 % DMBA dissolved in aceton, three times a week, at the same site. After macroscopic detection of cancer and the signs of cachexia (weight loss, etc.), Indian-ink was infused into the ascending aorta of each animal under general anesthesia. Tissue was harvested from each animal and made into a transparent specimen, 100 p m in thickness, for examination of vasucular architecture. The mode of cancer invasion was Grade I in 8 animals, Grade 2 in 8, Grade 3 in 23, and Crade 4C in 5. Macroscopic tumor growth mode was exophytic in 36 animals and endophytic in 8 animals. Each mode of cancer invasion was associa
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ted with characteristic vascular architecture. That is, low invasive cancers (Grade I and 2) showed dendriform vascularization and a marked increase in vessel density as they underwent exophitic growth. Grade 3 invasive cancei shbwed rings of blood vessels forming during the coume of invasion by alveolar tumor foci. Diffusely invasive cancer (Grade 4C) showed destruction of exisdng blood vessels and a decrease in vessel density. As fumor invasion progressed ; the vessel density decreased (p<0.05). The vessel density was significantly lower in cases of exophytic cancer than in cases of endophytic cancer (p<0.01). The PCNA (proliferating cell nuclear antigen) of cancer cells, which is an indicator of tumor proliferation potential, was more frequently positive as tumor invasion bccame more severe. That is, the PCNA positive rate in Grade I or 2 animals differed significantly from that in Grade 3 or 4C animals (p<0.05). The PCNA positive rate decreased as vessel density increased (p<0.05). Thus, the vessel density was not proportional to the tumor proliferation potential. The expression of vascular endothelial growth factor (VEGF) was seen more frequently as tumor invasion progressed (p<0.05), but the expression of VEGF did not correlate with the vessel density. These results suggested that the changes of the tumor vessel were dependent on the mode of cancer invasion and proliferation. Less
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