Estrogen receptor expression of benign breast epithelium and its association with breast cancer.

We conducted a case-control study of estrogen receptor (ER) and progesterone receptor (PgR) expression in benign breast epithelium from 120 women (51 breast cancer cases and 69 benign disease controls) who underwent breast operations at University Hospital, Syracuse, New York. Benign samples were obtained and processed immunohistochemically for ER and PgR (Abbott, Chicago, IL). Receptor positivity was defined as any nuclear immunostaining. Proportionately more cases than controls were ER positive (84% versus 57%); PgR positivity was similar in cases and controls (86%). Logistic regression yielded an adjusted odds ratio of 6.5 for breast cancer among ER-positive women (95% confidence interval of 1.5 and 27.4); odds ratio of PgR positivity was 0.3 (95% confidence interval of 0.1 and 1.9). Adjustment for known risk factors for breast cancer did not change the odds ratio. ER-positive breast epithelium needs evaluation as a possible risk marker for breast cancer.