ER positive status in Ca Breast indicates

The presence or absence of estrogen or progesterone receptors ; The presence of hormone receptors confers a slightly better prognosis. However, the practical reason for determining their presence is to predict the response to therapy. The highest rate of response (approximately 80%) to antiestrogen therapy (oophorectomy or tamoxifen) is seen in women whose tumor cells express both estrogen and progesterone receptors ref : Robbins Basic Pathology, 9E,page-713