CEACAM5 and gastric cancer: Numerous prognostic factors for gastric cancer have been reported, including the depth of tumor invasion [4], site of lymph node metastasis [4], number of metastatic lymph nodes [5–7] lymph node metastasis ratio [7–9], distant metastasis [4], results of peritoneal lavage cytodiagnosis [10, 11], tumor diameter [12], macroscopic type [13, 14], tumor location [15, 16], age [17, 18], sex [17], lymphatic invasion [19], venous invasion [20], histologic type [21], macroscopic serosal invasion [22], tumor markers (CEA and CA19-9) [23, 24], and extent of lymphadenectomy [24–26].