Antiestrogen medication used in treating breast cancer

• A. Tamoxifen
• B. Anastrozole
• C. Letrozole
• D. Fulvestrant

Answer: (A)

Blocking estrogen signaling in breast tissue is a key strategy for ER-positive breast cancer. Tamoxifen acts as a selective estrogen receptor modulator, binding to the estrogen receptor in breast cells and acting as an antagonist there. This prevents estrogen from activating genes that promote tumor growth, slowing or stopping cancer progression. It’s widely used as adjuvant therapy and for prevention in high-risk patients. The other drugs work differently: aromatase inhibitors like anastrozole and letrozole lower estrogen production rather than blocking the receptor, which suits postmenopausal patients but isn’t the classic receptor-targeted antiestrogen in the breast. Fulvestrant degrades the estrogen receptor itself, a separate mechanism from receptor antagonism. So the best answer for an antiestrogen medication used in treating breast cancer is tamoxifen.