Introduction 11 23 16 7 23 12 12 13 30 27 36 30 24 26 21 Helicobacter pylori 9 Materials and methods Subjects A total of 814 gastric carcinomas were collected from surgical resection in Kouseiren Takaoka Hospital between 1998 and 2006. The patients with carcinomas included 573 men and 241 women (29–91 years, mean = 65.7 years). Among them, 312 cases were demonstrated with lymph node metastasis and 24 with liver metastasis. None of these cases underwent either chemotherapy or radiotherapy before surgery. All patients gave their informed consent for the use of tumor tissue specimens for clinical research and the University Ethical Committee approved the research protocol. All patients were followed up by consulting their case documents and through telephone interviews. Pathology 25 7 16 30 26 Tissue microarray 1 Fig. 1 HE staining of TMA of gastric carcinomas  Immunohistochemistry 15 1 Table 1 Primary antibodies used in this study Names Source Company Dilution Ki-67 Rabbit DAKO, Carpinteria, USA 1:25 Caspase-3 Rabbit DAKO, USA 1:150 p53 Mouse DAKO, USA 1:100 FHIT Rabbit Neomarkers, Fremont, USA 1:200 Maspin Mouse Novocastra, Newcastle upon Tyne, UK Read-to-use EMMPRIN Mouse Novocastra, UK 1:100 VEGF Rabbit Labvision, Fremont, USA 1:50 9 Rabbit SAT, USA 1:300 MUC-2 Mouse Novocastra, UK 1:100 MUC-4 Mouse Novocastra, UK 1:100 MUC-5AC Mouse Novocastra, UK 1:100 MUC-6 Mouse Novocastra, UK 1:100 CD44 Mouse DAKO, USA 1:50 E-cadherin Mouse Takara, Otsu, Japan 1:100 β-Catenin Mouse Calbiochem, CA, USA 1:200 9 9 2 Fig. 2 a c d b g e 9 h i k l f j m n o  Statistical analysis U p Results Clinicopathological characteristics of gastric IT, DT, and MT carcinomas 2 p p p p p p Table 2 Comparison of the clinicopathological features in gastric IT, DT, and MT carcinomas Clinicopathological features Intestinal-type carcinoma Diffuse-type carcinoma Mixed-type carcinoma Case number 415 (51.0%) 221 (27.1%) 178 (21.9%) Age (mean ± SD, years) 67.09 ± 10.73 62.03 ± 11.3* 65.80 ± 13.28 Sex (male:female) 324:91 125:96 124:54** Tumor size (mean ± SD, cm) 3.82 ± 3.21 5.50 ± 6.95 5.56 ± 3.08** Invasion into muscularis propria 153 (36.9%) 121 (54.8%) 123 (69.1%)** Lymphatic invasion (+) 117 (28.2%) 83 (37.6%) 99 (55.6%)** Venous invasion (+) 49 (11.8%) 32 (14.5%) 39 (21.9%)** Lymph node metastasis (+) 113 (27.2%) 94 (42.5%) 105 (59.0%)** Liver metastasis (+) 10 (2.4%) 8 (3.6%) 6 (3.4%) Peritoneal spread (+) 14 (3.4%)*** 22 (10.0%) 21 (11.8%) TNM staging (O, I) 302 (72.8%) 69 (31.2%) 112 (63.0%)** p p p Pathological behaviors of gastric MT carcinomas with different growth patterns or histological distribution of components 3 p p Table 3 Pathological behaviors of gastric MT carcinomas Clinicopathological features n Sex (male) Invasion into MP Lymphatic invasion Venous invasion Lymph node metastasis Staging n I>D I=D I<D (O, I) Growth pattern            I 106 73 (68.9%) 82 (77.4%) 64 (60.4%) 26 (24.5%) 69 (65.1%) 32 14 23 35 (33.0%)  II 25 18 (78.3%) 21 (84.0%) 16 (64.0%) 7 (28.0%) 16 (64.0%) 5 5 6 7 (28.0%)  III 29 22 (75.9%) 11 (37.9%) 9 (31.0%) 3 (10.3%) 10 (34.5%) 4 3 3 18 (62.1%)  IV 4 1 (25.0%) 4 (100.0%) 4 (100.0%) 1 (25.0%) 4 (100.0%) 0 2 2 0 (0.0%)  V 14 10 (71.4%) 5 (35.7%) 6 (42.9%) 2 (14.3%) 6 (42.9%) 2 0 4 9 (64.3%) Histological appearance            Intestinal>diffuse 80 59 (73.8%) 54 (67.5%) 43 (53.8%) 20 (25.0%) 48 (60.0%) 30 8 10 33 (41.3%)  Intestinal=diffuse 20 15 (75.0%) 12 (60.0%) 9 (45.0%) 5 (25.0%) 10 (50.0%) 3 5 2 8 (40.0%)  Intestinal<diffuse 78 50 (64.1%) 57 (73.1%) 47 (60.3%) 14 (18.0%) 47 (60.3%) 10 11 26 28 (35.9%) MP I>D I<D I=D Immunohistochemical analysis of intestinal or diffuse components from three types of gastric carcinomas 4 p p p p 9 p Table 4 Immunohistochemical analysis in gastric IT, DT, and MT carcinomas Biological markers Intestinal-type carcinoma Mixed-type carcinoma Diffuse-type carcinoma Intestinal part Diffuse part Ki-67 , 81/110 (73.6%) 78/110 (70.9%)* 57/119 (47.9%) Caspase-3 84/152 (55.3%)* 52/119 (43.7%) 37/119 (31.1%) 24/115 (20.9%) p53 76/151 (50.3%)* 37/118 (31.4%) 30/118 (25.4%) 25/120 (20.8%) FHIT 90/150 (60.0%)* 63/113 (55.8%) 48/113 (42.5%)* 27/116 (23.3%) Maspin 71/150 (47.3%)* 55/112 (49.1%)*** 34/112 (30.4%) 38/120 (31.7%) EMMPRIN , 77/112 (68.8%)*** 43/112 (38.4%) 32/117 (26.5%) VEGF , 90/114 (78.9%)*** 61/114 (53.5%)* 31/121 (25.6%) 9 88/144 (61.1%)* 74/113 (65.5%) 67/113 (59.3%)* 48/116 (41.4%) MUC-2 , 31/118 (26.3%) 27/118 (22.9%) 23/117 (19.7%) MUC-4 58/153 (37.9%)* 39/118 (33.1%)*** 21/118 (17.8%) 18/118 (15.3%) MUC-5AC 84/148 (56.8%) 57/106 (53.8%) 50/106 (47.2%) 54/113 (47.8%) MUC-6 , 26/117 (22.2%) 18/117 (15.4%) 9/123 (7.3%) CD44 , 32/114 (28.1%) 31/114 (27.2%) 32/120 (26.7%) E-cadherin 91/142 (64.1%)* 58/112 (51.8%)*** 38/112 (33.9%) 43/119 (36.1%) Membrane β-catenin 57/144 (39.6%)* 36/117 (30.8%) 26/117 (22.2%) 26/118 (22.0%) p p p Patients' outcome with different gastric carcinomas 3 p p p 5 Fig. 3 IT DT MT  Table 5 Multivariate analysis of the clinicopathological variables of gastric carcinomas Clinicopathological parameters Relative risk (95% CI) p Age (≥65 years) 1.224 (0.849–1.764) >0.05 Sex (male:female) 1.255 (0.827–1.904) >0.05 Tumor size (≥4 cm) 1.466 (0.862–2.493) >0.05 s,1 T 2,3 2.945 (1.533–5.657) <0.05 Lymphatic invasion (−/+) 1.394 (0.865–2.247) >0.05 Venous invasion (−/+) 1.692 (1.097–2.608) <0.05 Lymph node metastasis (−/+) 1.983 (1.111–3.537) <0.05 Peritoneal spread (−/+) 3.197 (2.031–5.031) <0.05 Liver metastasis (−/+) 5.248 (2.575–10.697) <0.05 Lauren's classification (intestinal/diffuse/mixed) 1.351 (1.084–1.683) <0.05 CI Discussion 23 30 16 2 5 16 26 6 16 30 14 26 16 26 30 9 25 30 31 34 35 34 28 29 32 1 3 33 8 19 27 36 20 22 4 5 9 18 30 17 9 10 5 In summary, IT carcinoma, which is positively correlated with favorable prognosis, frequently displayed high levels of proliferation, apoptosis, angiogenesis, mucin production, and cell adhesion. Gastric MT carcinoma showed more aggressive behaviors than IT and DT ones. There was a significant difference in the proliferation, apoptosis, angiogenesis, mucin secretion, and cell adhesion between the IT and DT carcinomas, whereas only a few characteristics were differentially detected in the intestinal and diffuse component of the mixed-type carcinoma, suggesting that different components of MT carcinoma might originate from common stem cells, but follow distinct histogenic pathways. Furthermore, these results confirm that Lauren's classification is significant regarding the histopathogenesis and differentiation and considered as a guide to the clinical treatment of gastric carcinoma.