How would you approach treatment for a pre-menopausal patient with PR-positive, ER-negative, HER2-negative cT1c N1 breast cancer?

The prevalence of ER- PR+ HER2- breast cancer is relatively low and probably ranges from about 0-8%, with concerns about technical errors in HR status determination by IHC often being expressed in this instance. Because of this, I would consider repeat receptor testing at some point (an additional biopsy or on the surgical specimen) to ensure that these receptors are real.

However, a recent paper by Beltjens et al., PMID 33634878 suggested that ER- PR+ HER2- breast cancer is a real entity, with a prognosis closer to triple negative disease. These tumors were less likely to be low grade, and mostly stained with low to moderate intensity and less than 50% of the cells.

Based on the results of the RxPONDER data in PRE-menopausal women with node-...