Response of human tumor cells of varying radiosensitivity and radiocurability to fractionated irradiation.
The cytotoxic effects of radiation delivered in daily fractions of 2.0 Gy were examined in plateau phase cultures of human tumor cells of varying in vitro radiosensitivity, derived from tumors of varying radiocurability. Among the eight cell lines examined, three types of responses to fractionated irradiation were observed. In the group composed of tumor cell lines that were radioresistant in culture (D0 > 2 Gy) and derived from known local radiation failures or from tumor histologies associated with radiation failure, a gradual linear reduction in surviving fraction versus total dose was observed. In a second group, composed of cell lines that were radiosensitive in culture (D0 approximately 1 Gy) but derived from known radiation failures, the surviving fraction initially declined and began to plateau after 6 Gy (three fractions of 2 Gy). In the third group, composed of radiosensitive cell lines derived from tumors associated with high radiocurability, a rapid decline in surviving fraction versus total dose was observed. The in vitro response of human tumor cells to fractionated irradiation delivered at clinically relevant doses appears to be independent of in vitro X-ray sensitivity and p53 status but related to clinical radiocurability, suggesting a possible role in predicting tumor response to radiotherapy.
Dahlberg
W K
WK
Harvard School of Public Health, Laboratory of Radiobiology, Boston, Massachusetts 02115, USA.
Azzam
E I
EI
Yu
Y
Y
Little
J B
JB
D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000032:analysis; D019583:Dose Fractionation, Radiation; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy*; D011836:Radiation Tolerance; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D016159:Tumor Suppressor Protein p53