Aneuploid subpopulations in tumour-invaded lymph nodes from breast cancer patients

Fresh, paired primary tumours and lymph node metastases from breast cancer patients were compared by DNA flow cytometry. Although 65% of primary tumours were aneuploid, the detection of aneuploid peaks in corresponding nodal metastases was rare (only 6 cases out of 25) in single-parameter DNA analysis. Detection of aneuploid subpopulations in lymph nodes was greatly improved in dual-parameter DNA analysis using an anticytokeratin (CK) antibody which allowed ploidy determination on CK+ epithelial cells alone. Examination of 12 lymph nodes for CK+ cells revealed the presence of both diploid and aneuploid tumour cells in tumour invaded nodes. In patients with multiploid primary tumours, a subpopulation of the primary aneuploid cells was dominant in the nodal metastases. This suggests that aneuploidy is an integral property of metastatic cells and that within a primary tumour a subpopulation may have a higher metastatic potential.