Radiosensitivity of multicellular tumour spheroids obtained from human ovarian cancers.

The radioresponsiveness of immunologically characterised (KL1, antivimentin and OC125) human ovarian carcinoma cells, obtained from effusions or solid tumours, was assayed in vitro using the multicellular tumour spheroids (MTS) three-dimensional model. Great interspecimen variabilities were observed in MTS doubling time (1.0-8.5 days), as well as in the doses inducing a 50% decrease in the MTS individual volume (ID50) (0.56-9.15 Gy), or in the overall population MTS number (SCD50) (1.9-15.7 Gy) and the residual/initial MTS individual volume ratio after 2 Gy irradiation (RSV2) (10-88%). The doubling time, DNA-ploidy and S-phase fraction did not correlate with the ID50. Significant correlations were found between the new parameters defined (RSV2 and ID50) and the SCD50, a well-accepted local control parameter. These parameters demonstrated their usefulness for studying the radiosensitivity of MTS prepared from human ovarian tumour biopsies.