Understanding the difference between estrone (E1), estradiol (E2), and estriol (E3) is essential for women navigating hormone-positive breast cancer—especially those in natural or medically induced menopause. While most cancer treatments focus on lowering estradiol, new research shows that estrone may play a more influential role in inflammation, EMT activity, and cancer stem cell behavior. This article breaks down what estrone is, why testing it matters, and how to support h