What condition is tamoxifen used to treat?

Tamoxifen is primarily used to treat breast cancer, particularly hormone receptor-positive breast cancer. This medication acts as a selective estrogen receptor modulator (SERM), meaning it can block estrogen's effects in breast tissue, which is crucial because many breast cancers grow in response to this hormone. By inhibiting estrogen's action, tamoxifen can help to decrease the risk of cancer recurrence and improve survival rates for patients diagnosed with this type of cancer.

While the other conditions listed are important in the context of women's health, they are not treated with tamoxifen. Non-Hodgkin's lymphoma is typically managed with chemotherapy or targeted therapies. Endometriosis may be treated with pain management strategies, hormonal therapies, or surgical intervention but not specifically with tamoxifen. Polycystic ovary syndrome (PCOS) is addressed through lifestyle changes and medications like insulin sensitizers, not tamoxifen. Therefore, tamoxifen's specific role in targeting breast cancer management makes it the correct answer in this context.