What is a potential side effect of tamoxifen treatment?

Tamoxifen is a medication commonly used in the treatment and prevention of breast cancer, particularly in hormone receptor-positive cases. While it is effective in reducing the risk of breast cancer recurrence, it also has some potential side effects, one of the most significant being the increased risk of uterine cancer.

Tamoxifen acts as a selective estrogen receptor modulator (SERM). In breast tissue, it blocks estrogen's effects, which is beneficial in treating estrogen-receptor-positive breast cancers. However, in the uterus, tamoxifen can actually mimic estrogen, leading to increased stimulation of the uterine lining (endometrium). Over time, this stimulation can result in changes in the endometrial tissue, including a greater likelihood of developing endometrial hyperplasia and, subsequently, endometrial (uterine) cancer.

The other choices presented do not reflect the most significant or clinically relevant potential side effects of tamoxifen. While breast enlargement does not typically occur with tamoxifen, it can cause changes in breast size in some individuals due to hormonal influence. Weight loss is not generally associated with tamoxifen; in fact, some patients may experience weight gain. Finally, tamoxifen is known to decrease bone resorption and might lead to