[Application of the immunohistochemical method as predictive assay in radiotherapy of squamous cell carcinoma].

We analysed various subsets of lymphocytes infiltrated into cancer tissues from 15 patients (10 cases of oropharyngeal cancer and 5 of hypopharyngeal cancer) at pretreatment and at about 10 Gy and 30 Gy of irradiation by the method of biotin-avidin-horseradish peroxidase using mouse monoclonal antibodies. In 3 cases, tumor infiltrating lymphocytes were remarkably increased at the delivery of small dose of irradiation: Two of them showed remarkable radiosensitivity, and the lymphocyte subpopulation of the cancer tissue was mainly composed of Leu3a + 3b positive, Leu-8 negative and Leu-HLA-DR positive lymphocytes (activated helper inducer T lymphocytes). On the other hand, the third one proved to be rather radioresistant and the lymphocyte subpopulation was mainly composed of Leu-14 positive lymphocytes (B lymphocytes). These findings indicate that the analysis of the lymphocyte subpopulation infiltrating into cancer tissues at the delivery of small dose of irradiation is applicable as a predictive assay in radiotherapy of squamous cell carcinoma of oropharynx and hypopharynx.