How do you reconcile the difference with regard to adjuvant treatment recommendations when a breast biopsy reveals >10% ER+ but a subsequent lumpectomy of the same lesion is ER-negative?   

Situations such as this typically involve review with pathology, including a second opinion review, to settle on one of two basic camps of possible explanations: 1. Heterogenous cancer or even possibly multiple primaries with differing receptors. Although not common, some cancers are heterogeneous ...