Bone Marrow Only Metastases from Lobular Carcinoma: Insights into Responses to Endocrine Therapy

Abstract

Two patients with lobular carcinoma of the breast previously treated with curative intent presented with anemia and multiple areas of bone pain. CT/PET, bone scan and a panel of laboratory tests including peripheral blood smears were not abnormal except for their CA27-29 values. Bone marrow aspirates and biopsies were performed. In both patient’s lobular carcinoma was identified. They both failed on aromatase inhibitor-based regimens. Fulvestrant and abemaciclib were used as the first palliative option. Responses to this combination were marginal and brief. Substituting everolimus for the abemaciclib resulted in marked, rapid improvements in pain, anemia and CA27-29 levels. One patient demonstrated a tumor flare event.