COMPARISON OF CELLULAR RADIOSENSITIVITY BETWEEN DIFFERENT LOCALIZATIONS OF HEAD AND NECK SQUAMOUS-CELL CARCINOMA

The prognosis of carcinomas arising from various sites in the head and neck varies even when the stage of the disease is taken into consider ation, e.g. laryngeal carcinoma has a more favourable prognosis compar ed to oral-cavity malignancies. The purpose of this study was to evalu ate intrinsic cellular radiosensitivity as one possible explanation fo r the observed differences in the survival rates of different anatomic al groups. The radiation survival curves were determined for well char acterized cell lines derived from laryngeal carcinoma (n = 14), pharyn geal carcinoma (n = 6), carcinoma of the oral cavity (n = 14) and the skin of the face (n = 3). The intrinsic radiosensitivity was expressed as area under the survival curve (AUG) values, and this cellular para meter was compared with clinical data and survival of the patients. Th e intrinsic radiosensitivity in the whole group varied between 1.0 Gy and 2.8 Gy with an average of 1.9 Gy. The mean AUC values for the lary ngeal cell lines were 2.0 Gy +/- 0.2, for the oral cavity 1.8 +/- 0.3 Gy, for the pharynx 1.8 +/- 0.2 Gy and for cutaneous carcinoma 2.1 +/- 0.1 Gy. There was a slight difference between the groups of glottic a nd supraglottic cell lines (mean 1.8 +/- 0.2 Gy and 2.1 +/- 0.3 Gy, re spectively), which is consistent with the differences in clinical cura bility of these cancers. Otherwise, the differences in cellular radios ensitivity of the carcinoma groups studied did not reach statistical s ignificance. These results indicate that the intrinsic radiosensitivit y of squamous-cell carcinoma (SCC) of the larynx does not significantl y differ From that of SCC of other sites of the head and neck. Variati ons in the intrinsic radiosensitivity do not as such seem to explain t he observed differences in radiocurability of SCC variously localized in the head and neck.