Relationship of age and menopausal status to estrogen receptor content in primary carcinoma of the breast.

The cytosolic estrogen receptor (CER) content of 1037 primary breast carcinomas was evaluated by sucrose density gradient analysis. Tumor specimens from premenopausal patients had significantly lower levels of CER (14.6 +/- 1.5 (mean +/- SEM) 8S binding fmole/mg protein) compared with carcinomas from postmenopausal patients (57.5 +/- 3.9 fmole/mg protein; p less than 0.001). The proportion of specimens with CER levels above threshold values of 3, 7, or 10 fmoles/mg protein were significantly higher for postmenopausal patients (72%, 63%, 59%, respectively) than for premenopausal patients (56%, 42%, 36%, p less than 0.001). When compared within half-decades, no statistically significant differences between premenopausal and postmenopausal patients were observed for mean, median, or rank sums of CER levels (p greater than 0.3). When patients were compared by half-decades, both mean and ranked sums of CER levels were significantly different (p less than 0.001). The proportion of specimens that demonstrated CER levels above a threshold value of 10 fmole/mg protein increased sequentially from a low of 13/51 (26%) for patients less than 35 years to a high of 60/81 (74%) for patients greater than 75 years.