How do you approach a pre-menopausal female with HR+ breast cancer with discordant IHC and OncotypeDx ER expression?

There are multiple reasons this can happen. The RNA and protein for ER have different stability in FFPE, heterogeneity between the biopsy sample used for IHC vs the surgically resected tumor used for Oncotype, or a failure to properly amplify the transcript from the sample provided are some causes. I would treat her as ER+ based off the IHC. I don't use the single gene reports for treatment selection. But if her pathology is discordant with the Oncotype score (since a low ER will drive up the sc...