Why do we give antiestrogen drugs to women who have breast cancer ?

To slow growth: Most breast cancers are stimulated by estrogen and progesterone, the normal female sex hormones. When deprived of these hormones, the tumors often die. Consequently, breast cancer tumors are tested to find out if they are sensitive to these hormones. If so, medicines to block these hormones are given as part of the cancer treatment for breast cancer.

Breast cancers come: In different varieties. We can discern estrogen and Progesterone receptors on path speciments of breast ca. Only those that are er/pr+ will benefit from anti-estrogen drugs.

To slow growth: in those that are ER positive.