What is your approach to adjuvant therapy for patients with ER negative, PR positive early stage breast cancer?  

ER-negative but PR-positive is unusual (<5%) but not unheard of, and is worth repeating receptors to make sure is accurate.  Assuming confirmed, given uncertainty about the nature of these tumors, I treat them as I do ER borderline (1-9%) tumors, with endocrine therapy but some skepticism ab...

Does such an entity even exist? If it does, is it because of a false negative ER or a false positive PR? Does technical aspects of IHC staining influence the results? What would be the intrinsic subtype of the tumor? If it is luminal A/B, will anti-estrogen therapy matter in such patients? I ge...

Very small subset <5%. Some data suggests poorer prognosis for PR+/ER-. Because PR is an ER dependent protein product, we tend to be skeptic of true ER negativity, but it is possible that we may be seeing variation of expression within a tumor or technical issues. If encountered, I would general...