This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Estrogen positive breast cancer is best treated by which drug? 
Select and explain. 
A. Tamoxifen, B. Clomifene, C. Glutethemide, D. 5-FU
A: Tamoxifen
Answer: A: Tamoxifen 
Explanation: Ans. is 'a' i.e., Tamoxifen Drugs commonly used in hormone (estrogen) receptor positive breast cancer SERMs Tamoxifen, tromifene SERDs Fulvestrant o Aromatase inhibitors :- Letrozole, anastrazole, exemestone.