Study of radiosensitivity of differentiated thyroid human tumors by F.I.S.H. and the survival curves

This study deals with description of stable chromosomal anomalies radioinduced by 60Co or 131I, carried by tumoral and normal thyroid cells coming from I.G.R.-operated patients. After cell characterizing by immunofluorescence, these are irradiated at 0.5 - 5 Gy (the non-irradiated cells are serving as control cells). Portion of the irradiated cells is used to establish the survival curves by the classical clonal-genetics method, while another portion is fixed and displayed to get the in-situ hybridization (F.I.S.H.) of the 4-chromosome which does not carry aberration in this type of pathology. The tumoral cell radiosensitivity in terms of erroneous reparations (stable anomalies), measured by the F.I.S.H. is then compared with that of healthy thyroid and fibroblastic tissues as well as to that of the patient's own lymphocytes. The results obtained for the thyroid cells irradiated by cobalt are linear curves from 0 to 2 Gy and quadratic ones beyond; these obtained for the cells irradiated by iodine are straight lines between 0 and 1.5 Gy (the limitation to this dose range is due to the method). The survival curves of the cells agree with the results obtained by F.I.S.H.. The curves obtained by F.I.S.H. for the fibroblasts and lymphocytes are also linear-quadratic with low translocation percentages for the fibroblasts and rather high for lymphocytes. This preliminary results are suggesting a correlation between the translocation rate, obtained by the F.I.S.H. method, and the cellular survival obtained by the reference method (survival curves). In the case of thyroid tumors these results suggest a predictive value of F.I.S.H. concerning the radiosensitivity of the tissues, these technique presenting also the advantage of being more rapid