Discrepancies of DNA content of various solid tumours before and after culture measured by image analysis. Comparison of cytogenetical data

Parallel cytophotometric ploidy studies and cytogenetic analysis were performed on 15 various human solid tumours. The quantification of DNA by image analysis was carried out on cytological imprints of fresh tumours and on smears obtained after cell culture. The results obtained by both sets of calculations were compared with each other and with the cytogenetic results. 6 cases (40%) showed concordance between the 3 techniques. One case was aneuploid for both DNA image analysis measurements but the cytogenetic data showed only a diploid stem line. In 3 cases out of 15 (20%), smears DNA analysis and cytogenetic results were concordant: in 2 tumours, the culture step failed to preserve aneuploid stem lines that were present in the imprint analysis. In the third one, a minority tetraploid peak observed after culture was absent on the imprint slide. Concordance between imprints and cytogenetic data and discordance with smears' analysis was observed in 3 cases (20%). These 3 cases were diploid or near diploid but the DNA analysis on the smears after culture showed an aneuploid stem line in each case. The last 2 cases showed a total disagreement between the 3 techniques. By measuring the DNA content with an image analyser, the observer can ensure that only tumoral cells are taken into account. The present study revealed that cytogenetic data represent only about 60% of the population that is effectively present in the culture dish and that the cultured population represents only 47% of the population present on the fresh tumour imprint.