Abstract
Ten oral multiple cancer cases were used in the present clinical and histological in-vestigation. The 1st and 2nd tumors were observed simultaneously in 2 cases, and the remaining 8 cases of 2nd tumors occurred 11 months to 8 years and 11 months after treatment of each first tumor. Except in 3 cases, both 1st and 2nd tumors were associated with leukoplakia, erythroplakia and lichen planes. Eight and 9 cases of the 1st and 2nd tumors, respectively, were in the early T stage (T1 and T2), and they were almost well differentiated and nonsporadic in the tumor cell invasion, however, tumor cells in the 2nd tumors were slightly sporadic. In 4 patients with the 1st tumor positive for mutant type p53 protein, the 2nd tumors were also positive for this antigen. Seven cases of the 1st tumors expressed both PCNA and EGF-R, and 8 and 7 cases of the 2nd tumors were positive for PCNA and EGF-R, respectively. Both 1st and 2nd tumors were controlled finally without metastasis, however, local recurrence occurred in 2 cases each. These results indicate that oral multiple cancer is highly associated with precancerous lesions and condition, that the tumor cells possess ordinary growing activity in spite of low malignancy, and that oral tumor associating with precancerous lesion is preferable to be removed widely but not deeply.
