The Epithelial-Mesenchymal Transition Pathway in Two Cases with Gastric Metastasis Originating from Breast Carcinoma, One with a Metachronous Primary Gastric Cancer

Background: Metastases to the stomach are extremely rare and the metastatic pathway is not well understood. Objective: To present two unusual gastric metastases and a review of the literature regarding the pathway of Epithelial Mesenchymal Transition (EMT) in the metastatic cells. Method: The clinicopathological aspects of the two cases were presented in the light of the most recent patents. Data about patents were obtained from the online databases PubMed, World Intellectual Property Organization (WIPO) and Google patents. Results: In the first case, in a 73-year-old female, total gastrectomy was performed for a Gastric Cancer (GC) that was proved to be, based on the immunohistochemical features (positivity for mammaglobin and estrogen receptor and negativity for E-cadherin, β-catenin, CD44 and maspin), a metastasis from an invasive lobular carcinoma of the breast, that was later confirmed. In the second case, a 67-year-old female with invasive ductal carcinoma of the breast, which benefited from chemotherapy and mastectomy, presented a metachronous gastric adenocarcinoma with collision-type metastatic breast ductal carcinoma. The aggressiveness of the GC cells was induced through the E-cadherin/maspin pathway, while the CD44-related stem-like properties of the tumor cells induced the aggressiveness of ductal carcinoma. Conclusion: In females with breast cancer, a possible metastasis in the stomach should be taken into account. Maspin and VSIG1 are not involved in breast cancer histogenesis. The Wnt/β-catenin signaling is not involved in the lobular carcinoma progression. The CD44/HER2 positivity in ductal carcinoma cells might indicate high risk of distant metastasis and low response to chemotherapy.