What is the consequence of excessive estrogen and progesterone receptor activity in breast cancer?

Excessive activity of estrogen and progesterone receptors in breast cancer primarily leads to uncontrolled cell proliferation, which is a significant factor in tumorigenesis. Estrogen, in particular, promotes the growth and division of breast cells by binding to its receptor, initiating a cascade of signaling pathways that enhance cellular proliferation. Elevated levels of these hormones or heightened receptor activity can exacerbate this growth response, leading to an increased risk of tumor formation and progression.

In many breast cancers, especially those classified as hormone receptor-positive, tumor cells become dependent on these hormones for growth. when receptor activity is excessive, it can result in the proliferation of breast cancer cells beyond normal regulation, contributing to the development and advancement of the disease. This unregulated proliferation is a hallmark of cancer, where the normal controls on cell growth and division are bypassed, presenting a challenge for treatment and increasing tumor aggressiveness.