This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Pathology
50 yr old female presented with lump in right breast. She was diagnosed having Luminal A carcinoma. All are true about this cancer except ? 
Select and explain. 
A. M/C subtype, B. Best prognosis, C. ER/ PR negative, D. Response poor to paclitaxel
C: ER/ PR negative
Answer: C: ER/ PR negative 
Explanation: Luminal A breast cancer Seen in elderly females M/c subtype ER/ PR positive Her 2 /Neu negative Low proliferation rate Ki 67 : low Best prognosis among subtypes Responsive to hormonal chemotherapeutic agents like tamoxifen and aromatase inhibitors, Respond poorly to non- hormonal chemotherapy drugs like paclitaxel. Immunohistochemistry staining of a tissue biopsy specimen of luminal type A breast cancer: