ESR1 and invasive lobular breast carcinoma: A bilateral modified radical mastectomy was performed (Fig. 4), and the pathology results demonstrated that the right breast had an invasive lobular carcinoma (Fig. 5) with two lesions (~3×2×2 cm and 5×4×3 cm, respectively), axillary lymph node 29/31 metastasis, ER 8%, PR 90%, CerbB-2 (+/−) and Ki-67 <3%.