Question

Which of the following is a pure estrogen antagonist that can be used in the treatment of breast cancer?

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

Hint:

Estrogen-receptor (ER) positive breast cancers are treated with drugs that block estrogen action.

Answer 1

The Correct Option is A

Step 1: Understanding the question.
We need to find a pure estrogen antagonist (not a mixed agonist-antagonist) that is used in breast cancer treatment.

Step 2: Evaluate Option 1 - Fulvestrant.
Fulvestrant is a selective estrogen receptor downregulator (SERD). It binds to the estrogen receptor with high affinity and has no agonist activity at all. It causes receptor degradation. It is used in hormone receptor-positive breast cancer in postmenopausal women, especially when resistance to other antiestrogens develops. Fulvestrant is a pure estrogen antagonist. This is the correct answer.

Step 3: Evaluate Option 2 - Raloxifene.
Raloxifene is a SERM (Selective Estrogen Receptor Modulator). It is an antagonist in breast and uterine tissue but an agonist in bone. So it has mixed agonist-antagonist activity, not a pure antagonist.

Step 4: Evaluate Option 3 - Letrozole.
Letrozole is an aromatase inhibitor. It prevents conversion of androgens to estrogens, thereby reducing estrogen levels. It is not a receptor antagonist at all.

Step 5: Evaluate Option 4 - Tamoxifen.
Tamoxifen is also a SERM. It is an antagonist in breast tissue but an agonist in the uterus (which can cause endometrial cancer). So it is not a pure antagonist.

Step 6: Conclusion.
Only Fulvestrant is a pure estrogen antagonist with no agonist activity anywhere.
Answer: Option (1) — Fulvestrant