Ploidy, proliferative activity and estrogen receptor content in human breast cancer

Tumor samples from 80 patients with breast cancer (43 primary, 37 metastatic) were analyzed for ploidy and proliferative activity using DNA flow cytometry. Sixty‐one tumors (40 primary, 21 metastatic) were also analyzed for estrogen receptor content. Eighty‐five percent of all tumors had an abnormal DNA content. The majority of tumors were hyperdiploid (65%). Seventy‐three tumors had a unimodal ploidy distribution, while in seven cases two distinct aneuploid subpopulations were identified. The degree of ploidy abnormality was not related to extent of disease or menopausal status, but was higher (DNA index > 1.5) in poorly differentiated tumors (p = 0.05). ER‐positive tumors were more often diploid (7 of 31) than ER‐negative tumors (3 of 30, p = 0.16). DNA content was constant in biopsies from multiple sites in 5 patients with metastatic disease and in serial biopsies over the course of the disease. High proliferative activity (percent cells in S‐phase) was more often associated with ER‐negative tumors than ER‐positive tumors (p = 0.03). However, in all subgroups analyzed a wide range of values was noted. We conclude that flow cytometric analysis of cellular DNA content provides a rapid means of quantitating ploidy and proliferative activity in human breast cancer. Ploidy abnormalities were common, stable, and usually unimodal. Proliferative activity was inversely related to estrogen receptor content.