Fig. 2

Transcriptional regulation pathway by steroid hormones. a Image showing the role of aromatase inhibitors and tamoxifen in blocking steroid synthesis. Estradiol binds to estrogen receptor (ER), leading to dimerization and binding to estrogen response elements (ERE) activating estrogen-responsive genes leading to proliferation. Tamoxifen competes with estradiol for ER binding aromatase inhibitors decreasing the synthesis of estrogens from their precursors. b Contrast-enhanced CT images of the chest and abdomen in a 72-year-old woman with ER⁺ invasive lobular breast cancer treated with letrozole (aromatase inhibitor) and tamoxifen. CT of the chest shows multiple filling defects in the bilateral segmental pulmonary arteries (arrows), compatible with pulmonary embolism, an adverse event associated with tamoxifen