Abstract

PIP: Steroid receptor assays in advanced or recurrent breast cancer are now recognized as a method for predicting therapeutic response to endocrine therapy. ER (estrogen receptor) and PgR (progesterone receptor) were measured by sucrose gradient centrifugation. Breast cancer, benign mammary tumors, and normal mammary tissue were examined. Following extensive laboratory procedures, several results were observed. The specific binding of ER was observed at the 8S as was the binding of PgR. 45% of human breast cancers were ER(+) and about 20% were PgR (+), with the positive rate of PgR lower than that of ER. All normal mammary tissues were ER (-) and with the benign mammary tumors, 1 of 10 fibroadenomas and 1 of 3 giant fibroadenomas was ER (+). Positive rates of ER and PgR were similar between premenopausal and postmenopausal females and across blood types A, B, and O. ER and PgR were negative in AB blood. The occurrence of ER in 10 cases of primary tumor and in metastatic or recurrent lesions was almost identical and binding sites were at almost the same level. Where both ER and PgR were measured in 39 cases, the 8 cases of PgR (+) showed ER (+) and there was a close relationship between the 2. With ER (+), papillotubular carcinomas tended to be lower than other histological types; in binding sites of ER, medullary tubular carcinoma occurred more frequently than schirrous carcinoma. Medullary tubular carcinoma occurred more often in the PgR. In 21 cases where the clinical response to endocrine therapy and the occurrence of ER were measured, 50% (6) of ER (+) and 25% of ER (+) or (-) displayed a response with 5 ER (-) cases showing no response. Endocrine therapy in 11 of 39 above mentioned cases was carried out with cases of ER (+) and PgR (+) responding better than those of ER (+) only. (Author's modified)