Autoradiographic in vitro study of the cell kinetics of osteogenic sarcomas and Ewing's sarcomas in children.

Proliferation kinetic parameters of 9 osteogenic sarcomas (6 primary tumours, 3 lung metastases) and 3 Ewing's sarcomas were determined using an autoradiographic in vitro method (single and double labelling with 3H- and 14C-thymidine, and 3H-uridine). Osteogenic sarcomas and Ewing's sarcomas, respectively, showed clearly individual pattern of proliferation. The following values were obtained: The average 3H-thymidine labelling indices of 13.8/8.7%, the DNA synthesis times of 12.2/14.4 hours, mitosis times of 1.1/1.9 hours, and mean cell cycle times of 58.0/78.2 hours. The potential tumour doubling times determined with the inclusion of the growth fraction averaged 4.8/5.0 days. Using 3H-uridine labelling of tumours, autoradiography allowed the determination of the growth fraction fair accuracy. It is between 0.26 and 0.71 for osteogenic sarcomas, the average being 0.49. In vitro results were compared with the volume doubling times of metastases of osteogenic and Ewing's sarcomas, reported in the literature which had been determined from series of lung radiographs. The importance of cell kinetic studies of human tumours therapy is demonstrated by a "cell kinetic therapy index".