Estrogen and progesterone receptor-positive breast cancer patients account for about 60% or more of the total number of patients in China. Patients with hormone-dependent breast cancer all require endocrine therapy to reduce tumor recurrence by pharmacologically blocking estrogen receptors, inhibiting estrogen synthesis, and lowering estrogen levels.
Commonly used drugs for endocrine therapy include tamoxifen, toremifene, and aromatase inhibitors (letrozole, anastrozole, exemestane), among others.
- The preferred endocrine treatment option for postmenopausal patients is an aromatase inhibitor, which directly blocks estrogen synthesis and reduces the body’s own estrogen production levels. However, at the same time, the bone is deprived of estrogen regulation, and the activity of osteoblasts (cells that can turn into bone tissue) is reduced and the activity of osteoclasts (cells that can destroy bone tissue) is increased, further accelerating the process of osteoporosis in postmenopausal women and increasing the risk of fracture dramatically.
- A subset of premenopausal breast cancer patients will also choose pharmacologic ovarian function inhibitors (goserelin, leuprolide, etc.) to bring the body to a postmenopausal state, and the dramatic reduction in estrogen will also exacerbate bone loss.
Endocrine therapy is usually a long-term process, with the standard length of treatment being 5 years, and even longer for up to 10 years for patients with certain tumor risk factors. Therefore, breast cancer patients on endocrine therapy should pay more attention to bone health to avoid excessive bone loss.