Radiation-resistant and repair-proficient human tumor cells may be associated with radiotherapy failure in head- and neck-cancer patients.

Inherent cellular radioresistance and repair of x-ray damage was studied in 19 early-passage squamous cell carcinoma lines derived from head- and neck-cancer patients with known clinical results following radiotherapy. Human tumor cells that were radioresistant and/or proficient in accumulation/repair of x-ray damage were cultured from patients unsuccessfully treated with radiotherapy. Thus, the presence of radiation-resistant and repair-proficient tumor cells was associated with clinical radiation failure, suggesting the possibility of a predictive assay based on in vitro radiobiological parameters.