Relationship of flow cytometry results to clinical and steroid receptor status in human breast cancer.

Flow cytometry (FC), estrogen receptor (ER), and progesterone receptor (PR) analyses were performed on 226 breast cancers. The presence of steroid receptors was inversely proportional to proliferative index and percent aneuploidy. Within the two ER (+ and -) groups, the presence of PR did not add significantly to the comparison. The mean proliferative index for the diploid tumors was 17.5 +/- 6.8 compared to 27.8 +/- 9.8 for aneuploid tumors (p less than .001). The degree of aneuploidy, or DNA index, was not related to cell cycle kinetics or steroid receptor status. In 163 tissues analyzed for percent tumor present, a correlation between the relative number of aneuploid cells and percent tumor in the histologic review was observed. A study of the diploid tumors indicated greater than 75% had at least 10% tumor cells by histologic review. Since with FC one can observe at least 10% aneuploid cells in a tumor sample, it is our opinion that the percent aneuploidy in this study is not artifactually low due to sampling error. There was no significant relationship between nodal status or number of positive nodes and proliferative index, aneuploidy, or steroid receptor status. Metastatic tumors had a higher mean proliferative index, but this was not statistically significant. There was a relationship between age and proliferative index but not between age and ploidy status. In a small group of patients there was a trend for proliferative index and percent aneuploidy to be higher in the poorly differentiated and larger tumors when compared to the well differentiated and smaller tumors.