Expression of oestrogen receptor and loss of E-cadherin are diagnostic for gastric metastasis of breast carcinoma

Aims : To investigate whether immunohistochemical staining for oestrogen receptor (ER)α, progesterone receptor (PgR) and E‐cadherin might be useful to differentiate between metastatic breast carcinoma and primary gastric carcinoma. Methods : Gastric biopsies of 75 patients containing adenocarcinoma were stained for ERα, PgR and E‐cadherin. Included were: Group A, 28 patients with primary gastric cancer; Group B, 28 patients with an adenocarcinoma containing gastric biopsy and a clinical diagnosis of metastatic breast carcinoma; Group C, all consecutive patients with a positive gastric biopsy in 2001 (n = 19) without clinical history of breast carcinoma and not followed by gastric resection (control group). Results : All ERα+ or PgR+ carcinomas (n = 20) were of patients with a previous or concurrent history of breast carcinoma: 19 in group B, one in group C. In addition, absence of E‐cadherin staining was seen significantly more often in patients with metastatic breast carcinoma than in patients with primary gastric cancer (P