DMBA誘発ハムスター舌癌のリンパ節転移に関する組織化学的研究

抄録

We examined whether the number and the distribution of blood and lymphatic vessels around tumors correlate with the frequency of lymph node metastasis. Ninety-one squamous cell carcinomas of the tongue of golden hamsters were induced by DMBA. After the development of tumors, the hamsters were divided into two groups: 42 given no additional treatment (Group A) and 49 in which surgical incisions were made in the center of the tumor once a week (Group B). The animals were killed when they showed obvious weakening or a body weight of less than 70g. The tongue tumors, lymph nodes, lungs, and liver were excised and frozen in OCT compound at -80°C until use. Each tumor was divided into anterior, middle, and posterior parts, and each part was graded for histological malignancy on the basis of the Anneroth classification, immunohistochemical characteristics of type P1 collagen (basement membrane staining), factor VIII-related antigen (blood vessel staining), and 5'-nucleotidase (5'-Nase: lymphatic vessel staining). The number of blood vessels and lymphatic vessels were counted per 200 fields in the areas most active for factor VIII and 5'-Nase, respectively. All lymph nodes were inspected for metastasis by examination of subserial, 100-μm interval, H-E-stained sections. Metastatic lymph nodes were histologically detected in 9 (21.4%) of the 42 animals in group A and 21 (42.9%) of the 49 animals in group B. The incidence of lymph node metastasis was significantly higher after repeated incisions of the tongue tumor. No metastasis to the lung or liver was detected. The relations between multiple variables and metastasis were assessed by multiple logistic regression analysis. Surgical incisions, the number of blood vessels, and the number of the lymphatic vessels were found to be significant risk factors for lymph node metastasis. These results indicate that lymphangiogenesis as well as angiogenesis may play an important role in the lymph node metastasis.