What medication is most likely prescribed for a client with an estrogen receptor-positive breast tumor post-surgery?

Tamoxifen citrate is most frequently prescribed for clients with estrogen receptor-positive breast tumors following surgery, primarily due to its specific mechanisms of action and established guidelines. Tamoxifen is a selective estrogen receptor modulator (SERM) that binds to estrogen receptors on breast cancer cells, inhibiting their growth by blocking the effects of estrogen.

This medication is particularly effective in premenopausal women and is often used as adjuvant therapy to prevent cancer recurrence after surgery. Tamoxifen is recommended based on the positive response in hormone receptor-positive breast cancer patients and has a well-documented history of reducing the risk of recurrence and improving overall survival rates.

While aromatase inhibitors, such as letrozole, are also used for treating estrogen receptor-positive breast cancer, they are more commonly prescribed for postmenopausal women. Raloxifene, though it has some use in osteoporosis prevention and treatment, is not primarily indicated for breast cancer. Therefore, in the context of a client post-surgery with an estrogen receptor-positive tumor, tamoxifen citrate is the most appropriate choice.