One of the proteins inside cells is known as the progesterone receptor (PGR). Progesterone, a steroid hormone, activates it. One PGR gene in humans is responsible for PR encoding. The progesterone receptor, a member of the steroid receptor superfamily, mediates progesterone’s action in its target sites or tissues. Progesterone’s role in breast cancer and mammary gland development is mediated by the progesterone receptor. Doctors have long known that women who are “double-positive” for both progesterone and oestrogen receptors have the greatest prognosis for surviving breast cancer because they respond to treatment more effectively and have a lower risk of the disease spreading.
Breast cancer cells may include progesterone and oestrogen receptors. These receptors enable the growth of cancer cells that are dependent on progesterone and oestrogen, among other related hormones. Many hormonal processes in women, including pregnancy, sexual development, childbirth, and menopause, are influenced by the hormones oestrogen and progesterone. Breast cancer is referred to as ER-positive breast cancer if its cells express oestrogen receptors. Breast cancer is referred to be PR-positive breast cancer if the progesterone receptors are present. Cancer is referred to as ER/PR-negative if the breast cells do not express any of these two receptors. ER or PR positive breast cancers make up about two thirds of all cases.