What effect does systemic estrogen therapy (ET) typically have on fibroids after menopause?

Systemic estrogen therapy typically plays a significant role in the behavior of fibroids after menopause. While estrogen is known to stimulate the growth of uterine fibroids, after menopause, the natural decline in estrogen levels usually leads to a decrease in fibroid size. In the context of systemic estrogen therapy, the introduced estrogen can promote further growth of these fibroids in premenopausal women, but the dynamic changes after menopause.

The correct answer reflects the understanding that fibroids often shrink after menopause purely due to the natural reduction in estrogen production and the altered hormonal environment. Since systemic estrogen therapy may stimulate fibroids, in the context of menopausal women where the therapy is administered, the overall trend is for treated fibroids to respond by shrinking rather than continuing to grow.

While the other options suggest that fibroids may grow larger or remain unchanged, it is essential to recognize that fibroids typically respond negatively to the reduced hormone levels post-menopause, leading generally to a decrease in size. The notion that they could become cancerous is also misleading, as fibroids themselves are benign tumors and not directly implicated in cancer development, although any changes in the structure of fibroids should be monitored clinically.