Advances in the detection of ploidy differences in cancer by in situ hybridization

Three main techniques allow the detection of changes in the cellular genomic content. The karyotyping procedure on metaphase spreads can give specific information on chromosome number and structural chromosome changes, but analyses are restricted to a limited number of chromosome spreads. Furthermore, cell culturing of (in particular solid) cancer specimens can result in selection of a minor tumour cell population with a high proliferative capacity. On the other hand, flow cytometry allows the analyses of large numbers of cells, but does not detect small variations in the DNA content or structural changes. The fluorescent in situ hybridization (FISH) procedure combines the advantages of the two former procedures, in that relatively large numbers of cells can be analysed easily and specific chromosomal changes can be detected.