In this case, the immunohistochemistry of gastric metastasis was ER (90%), PR (-), Ki67 (2%), GATA3 ( +), CK (AE1/AE3) ( +), CK7 ( +), and CK20 (-), suggesting that the tumor originated from the breast and was considered as gastric metastasis of invasive lobular carcinoma of the breast. This evidence concerns the gene ESR1 and invasive lobular breast carcinoma.