NUCLEAR-DNA CONTENT OF HUMAN BREAST-CARCINOMA - A COMPARISON OF RESULTS OBTAINED BY MICROSPECTROPHOTOMETRY AND FLOW-CYTOMETRY OF PARAFFIN-EMBEDDED TISSUE

This study compares 2 techniques for estimating the nuclear DNA conten t of tumor cell lines: (i) static cytometry of smears taken from fresh tissue and (ii) flow cytometry of cells extracted from paraffin embed ded tissue. Parallel determinations of DNA content, using both techniq ues, were made on samples of tissue taken from 130 female patients wit h breast carcinoma. Using a simple classification into diploid and non -diploid groups, the 2 techniques yielded discrepant results in 11% of cases. The most frequent causes of disagreement were (a) the inabilit y of static cytometry to distinguish between a diploid and a near-dipl oid peak and (b) for flow cytometry, the difficulty of determining whe ther a minor peak in the tetraploid region represented the G2 peak of a diploid cell line or the G0/G1 peak of a tetraploid cell line. If it is deemed necessary to accurately assess ploidy status, flow cytometr y on paraffin embedded tissue, using modern statistical programmes, wo uld seem to be most practical for routine use, but some neoplasms, par ticularly those with an equivocal ploidy peak in the tetraploid range by this method, will require static cytometry to accurately assess nuc lear DNA content. Using this approach, it appears that the disagreemen t between the 2 techniques would be less than 5%.