Clinical application of estrogen receptor in breast cancer.

Patients with ER positive primary tumors usually have initial metastases at the more favorable sites. Twelve out of 14 patients with ER positive had first site of metastases in either bone or soft tissue. In contrast, 13 of 17 patients with negative ER developed first metastases in viscera. ER positive patients respond better to endocrine therapy and survived twice as long as negative ER patients from the onset of recurrent cancer until death. ER content is not a sufficient criterion for the prediction of the response to endocrine manipulation but serves as useful supplementary information to clinical judgement in to selection of systemic therapy. Prior employment of radiation therapy or the administration of hormones or antihormones, as well as inadequate tumor cells in the specimen and poor procurement of the tumor, can produce spuriously low ER. A protocol to study simultaneous endocrine and chemotherapy in comparison to the sequential approach of endocrine treatment followed by chemotherapy in ER positive patients is desirable.