[The radiosensitivities of human neuroblastoma in vitro--a comparison of three cell lines]

The radiation response of three human neuroblastoma cell lines (GOTO, NB1M, and SINCG) has been studied in vitro, using single cells both in the exponentially proliferative and the plateau phases. The endpoint used was clonogenic cell survivals. Cell survival curves, obtained from all cell lines, were characterized by small D0 values (0.4-0.55 Gy). However, only the GOTO cells showed the lack of a shoulder in the survival curve, whereas the other cell lines, especially the SJNCG, showed a broad sized shoulder. Delayed assay experiments with SJNCG cells showed larger repairs of potentially lethal damage, both in the exponentially proliferative and plateau phases, in contrast to GOTO cells. Further, the cell capacity for a split dose recovery was greater in SJNCG cells than in the GOTO cells. It has been said that hyperfractionation radiotherapy might be a better treatment for a neuroblastoma than the conventional therapy, however, we would suggest that a modification of the radiotherapy schedule ought to depend on the type of cells, because there are cells which show broad shoulder curves and a strong capacity for repair.