HR-positive breast cancer is the most common type of breast cancer, accounting for approximately 80% of cases.¹ Breast cancers are considered HR-positive when tumour cells produce abnormal amounts of receptors for the hormones, estrogen and/or progesterone. As these hormones signal cells to grow and divide, having too many receptors on the surface of a cell can cause uncontrolled growth and the formation of a tumour. HR-positive breast cancers are commonly treated with medicines, known as hormone therapies, that block the activity of Estrogen Receptor (ER) and/or Progesterone Receptor (PR), or that reduce hormone levels.
Original article from: https://www.roche.com/stories/about-breast-cancer, accessed February 2002
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References:
- WebMD, Types of Breast Cancer: ER Positive, HER2 Positive, and Triple Negative. [Online]. Available from: https://www.webmd.com/breast-cancer/breast-cancer-types-er-positive-her2-positive, Accessed July 2024.