In vitro effects of bleomycin on a carcinoma of the oesophagus cell line.

A dose of 10 microgram/ml bleomycin inhibited the growth of oesophageal carcinoma cells and non-squamous cells in vitro. Drug concentration, density of cells and the time of exposure to the drug were important variables. The oesophagus cancer cells increased in volume by 2,5 +/- 0,2% per hour until the onset of lysis at 96 hours. The effects of the drug were irreversible even when the exposure time was only 24 hours. A certain proportion of the cell population was resistant to bleomycin and these cells remained resistant when the drug was removed for 48 hours and then replaced. No drug inactivation or uptake could be detected with the use of microbiological assay after 4 days of incubation with 3 cell types. There is poor correlation between in vitro and in vivo results.