Expression of estrogen receptor alpha and progesterone receptor in normal human breast epithelium

Recently, the immunohistochemical detection of estrogen receptor alpha (ERalpha) expression in breast cancer has become a prerequisite for therapeutic decision-making, however, it remains unknown whether ERalpha or progesterone receptor (PgR) expression in histologically normal breast epithelium (NBE) adjacent to carcinoma can be a reliable internal positive control.

Tissues from a total of 220 breast cancer patients were investigated by immunohistochemistry of ERalpha and PgR expression in NBE adjacent to carcinoma, as well as in carcinoma. The expression pattern was divided into three groups: singular, one or two positive cells; scattered, scattered positive cells surrounded by negative cells; contiguous, ten or more positive cells in contact with each other.

In NBE adjacent to carcinoma, the positivity of ERalpha and PgR was 99% (217 out of 220) and 89% (195 out of 220), respectively. The expression pattern of ERalpha and PgR was as follows: singular - 13 and 42 patients, scattered - 116 and 100 patients, and contiguous - 88 and 53 patients, respectively. The contiguous expression pattern of PgR was more frequently noted in premenopausal patients in contrast with ERalpha (p=0.0004). PgR expression was more frequently seen in premenopausal than postmenopausal patients (p=0.0034). PgR expression in carcinoma was more frequently seen in premenopausal than postmenopausal patients (p= 0.009). There was statistically significant correlation between PgR expression in carcinoma and NBE adjacent to carcinoma (p=0.0019).

These findings suggest that more frequent PgR expression in NBE adjacent to carcinoma might be correlated with carcinogenesis in premenopausal breast cancer patients and that ERalpha expression, not PgR, in NBE adjacent to carcinoma could be a reliable internal positive control.