Radioresistant and repair proficient cells may determine radiocurability in human tumors

Radiosensitivity and repair of radiation damage was studied in 29 human tumor cell lines. Nine tumor lines appeared radioresistant (RAD+) and were associated with radioincurable tumors. When the ability to repair potentially lethal damage was studied in plateau phase cultures, some tumor cell lines derived from radioincurable tumors were more efficient in this process (PLDR+). The results suggest that the presence of radioresistant or repair proficient cells may be responsible for local failure following radiotherapy. Advancements in cell culture and molecular biology may lead to predictive assays useful to clinicians.