Question

All of the following are true about fulvestrant (a selective estrogen receptor downregulator) except:

• A. Used for treatment of advanced breast cancer
• B. Also known as a pure anti-estrogen
• C. Is slower acting, has shorter duration of action and lower safety profile than SERMs
• D. Administered as a once-monthly intramuscular injection

Hint:

This SERD is a long-acting depot with a clean pure-antagonist profile.

Answer 1

The Correct Option is C

Step 1: Understand fulvestrant. It is a selective estrogen receptor downregulator (SERD) that binds the estrogen receptor, blocks it completely and accelerates its degradation, so it has no estrogen-agonist activity, making it a pure anti-estrogen (option B is true).
Step 2: Indication. It is approved for hormone-receptor-positive advanced or metastatic breast cancer, usually after progression on other endocrine therapy (option A is true).
Step 3: Route. Because of poor oral bioavailability it is given as a long-acting intramuscular depot injection, classically once monthly (option D is true).
Step 4: Evaluate option C. As a depot, fulvestrant actually has a long duration of action, and because it lacks the partial agonist effects of SERMs (like tamoxifen) it avoids endometrial and thrombotic agonist risks. So the statement that it is slower acting, shorter acting and lower in safety than SERMs is false.
Step 5: The exception (false statement) is option C.