In vitro sublethal damage repair in tumour subpopulations from a heterogeneous human colon tumour.

The repair of sublethal radiation damage in two asynchronously growing tumour cell subpopulations (clones A and D) obtained from a single human adenocarcinoma biopsy specimen has been studied. The survival data found after generation of complete survival curves from split dose experiments in which exposures were separated by 3, 6, 12, or 24 h were examined. It was found that the method of performing irradiations (e.g., suspension cultures versus monolayer cultures) affected the shape of the single dose response curves, and as a result the interpretation of the amount of sublethal damage repair occurring after split dose irradiation.