Abstract
Thirty-five T1 squamous cell carcinomas of the oral cavity underwent clinical and histopathological investigation and the results were as follows: 1) Recurrence was not observed in tumors which were resected with more than 1 cm of surgical safe margin (SSM), and 10 of 25 tumors which were resected with less than 1 cm of SSM revealed recurrence. 2) The mode of epithelial dysplasia around invasive carcinoma was classified into 3 types. Compared to tumors with type I dysplasia (localized mild dysplasia around the invasive carcinoma), those with type II (widely spreading severe dysplasia) and type III dysplasia (multifocal severe dysplasia with multifocal invasive carcinomas) recurred more often. 3) Lymph node metastasis was observed in one tumor before treatment and late metastasis occurred in 5 patients in whom 3 tumors were grade 3 in mode of tumor cell invasion. These results indicated that T1 tumor should be resected with more than 1 cm of SSM and late lymph node metastasis tends to occur in T1 tumors, especially in those exhibiting grade 3 invasion mode, and that oral multifocal dysplasia may result in multicentric carcinogenesis.
