Estrogen receptor positivity

Estrogen receptor positivity refers to the presence of specific proteins called estrogen receptors on or inside breast cancer cells. These receptors can bind to the hormone estrogen, which may fuel the growth of the cancer. When a cancer is estrogen receptor-positive, it often responds well to hormone therapies that block estrogen's effects, helping to slow or stop its growth. Testing for estrogen receptor status helps doctors determine the best treatment approach and provides information about the cancer's likely behavior and prognosis.