What is the most common type of breast cancer that hormone therapy targets?

Hormone receptor-positive breast cancer is the most common type targeted by hormone therapy because it expresses estrogen and/or progesterone receptors, making it responsive to hormone-based treatments. These therapies work by either blocking the hormones from attaching to the receptors on cancer cells or by lowering the levels of these hormones in the body. Since this subtype of breast cancer relies on hormones for growth, hormone therapy can effectively reduce tumor size and prevent recurrence.

Triple-negative breast cancer, while a significant subtype, does not have hormone receptors and therefore does not respond to hormone therapy. Likewise, HER2-positive breast cancer targets human epidermal growth factor receptor 2 (HER2) rather than hormone receptors, meaning it requires a different treatment approach. Invasive lobular carcinoma can be hormone receptor-positive, but it is not as commonly targeted by hormone therapy as hormone receptor-positive breast cancer in general, which includes types like invasive ductal carcinoma. Thus, the focus on hormone receptor-positive implications reinforces the appropriateness of hormone therapy in managing this prevalent cancer type.