Colony-forming ability of human ovarian carcinomas in the Courtenay soft agar assay

One hundred and twenty-one ovarian carcinomas were cultivated in soft agar according to the Courtenay & Mills (C-M) soft agar method. 71% of the tumours formed colonies, and 54% formed more than 30 colonies. Tumour cells from malignant fluids grew more frequently than did solid tumours, whereas the plating efficiencies (PEs) were higher in the case of solid tumours. In general, the PEs were higher and more tumours formed colonies in the C-M method compared to the Hamburger-Salmon (H-S) method. The colony-forming ability did not show statistically significant correlation to histopathological type and grade, previous treatment and S-phase fraction, but was related to DNA ploidy. In poorly differentiated tumours a high colony-forming ability was associated with a poor prognosis, whereas the opposite was found in well and moderately differentiated tumours. Differential dose-response relationships were obtained after in vitro treatment with anticancer agents.