Cellular X-ray repair parameters of early passage squamous cell carcinoma lines derived from patients with known responses to radiotherapy.

We have investigated X-ray survival parameters and repair of potentially lethal damage ( PLDR ) in ten early passage squamous cell carcinoma cell lines derived from patients who were biopsied before initiation of radiotherapy or after radiation therapy failure. Radiosensitivity (D0) ranged from 1.07 to 1.93 (Gy), extrapolation numbers (-n) from 1.17 to 2.14 and PLD recovery at 24 h from 1.4 to 20.3. Despite significant differences in these parameters amongst the cell lines, a firm correlation between radiocurability and any individual radiobiological parameter could not be established. Our data suggest that the mechanisms associated with radioresistance are complex and that any single radiobiological parameter may not predict clinical success or failure.