Cytogenetic Changes Following Thorotrast Administration

SummaryThe results are given of a cytogenetic study on 36 patients who had received Thorotrast by intra-arterial injection from 11–31 years previously.Unstable chromosome damage was found in 9·2 per cent of the cells examined; many cells contained more than one aberration, and 3·8 tricentrics were found per 100 cells analysed. No correlation was found between the numbers of unstable aberrations or the estimated number of chromosome breaks and either the volume of Thorotrast given or the number of years which had elapsed since its administration. Reasons for this lack of correlation are discussed. When the mean values for males and females were compared there appeared to be no sex difference.5·7 per cent of cells examined contained only stable chromosome re-arrangements. In two patients cells containing the same chromosome re-arrangement were found on separate occasions and in sufficient numbers to indicate their origin from lymphocyte clones in the peripheral blood of these individuals.