Cytogenetic studies on human breast carcinomas

Cytogenetic studies were performed on cell material obtained from surgical specimens of 50 human breast carcinomas and from 61 cancerous effusions of 46 patients. Classical cytogenetic analyses of numerical chromosome changes and marker chromosomes revealed the non-random involvement of chromosomes #X and #22 as monosomics, of chromosomes #3, #7, and #19 as trisomics, and chromosome #1 (particularly p 13 to q 12) in marker formation. Karyotypic evolution was followed in vitro and in vivo and showed a highly individualistic pattern of stability and variability. In addition, a systematic screening for the presence of cytogenetic equivalents of gene amplification (double minutes 'DM', homogeneously staining regions 'HSR') was carried out. A high incidence of DM-positive cases was detected in primary tumors (48%) as well as in metastatic cells from effusions (40%), with the frequency of DM-containing metaphases ranging from 1 to 100% in the positive cases. This finding supports the assumption of the fundamental biological importance of gene amplification in human solid tumors. Furthermore, chromosome breakage and micronuclei were observed in breast carcinoma cells as an apparent consequence of therapy-independent mutability.