A total of 144 patients with squamous cell carcinoma of the tongue treated by irradiation during the 14-year period from 1966 to 1980 were analyzed. The patients were classified into 3 groups according to the response to therapy, i. e. remission, recurrence and residual groups. Forty-two patients (29%) had recurrence and twenty-six (18%) had residual tumor. The 5-year determinant survival rate for the former is 48% and 43% for the latter. No correlation was found among the clinical factors in

more »

... e recurrence group. Howcver, in every recurrent case of Ra interstitial irradiation, a "cold area" was found near the center of the tumor using the computerized irradiation dose distribution map. In a recurrent case after intraoral electron therapy, tumor cells were found to involve the genioglossal muscle undernearth the primary lesion during microscopic evaluation of the sections. Biopsied specimens were available from 82 patients and were analyzed histopathologically according to Willen's method. Significant differences were observed in the nuclear polymorphism, mode of invasion, stage of invasion, and cellular response between the remission and recurrence groups, and between the remission and residual groups. Based on the above findings, it appears that tongue cancers with a Willen's score of 9 or less have the best prognosis following radiotherapy. Using the alpha-naphtyl acetate esterase staining and alkaline phosphatase staining techniques, T-lymphocytes were located at or near the tumor nest and B-lymphocytes were found far from the tumor nest, respectively.