The clinicopathological features of gastric cancer (GC) differ between younger and older patients, and it is thought that younger patients have a worse prognosis than older patients due to delayed diagnosis and more aggressive tumor behavior. These characteristics, however, remain controversial. A total of 3,818 patients with pathologically confirmed primary gastric adenocarcinoma were treated at our institution. We analyzed the difference in demographic and clinicopathological characteristics between 169 young [≤40 years of age, younger group (YG)] and 3,649 older [>40 years of age, older group (OG)] GC patients. There was a significantly higher proportion of females in the YG compared with the OG (53.3 and 31.0%, respectively; P<0.0001). The 5-year overall survival of the YG was significantly lower compared to that of the OG (59.7 and 65.9%, respectively; P=0.049). However, YG patients with curative resection had a similar 5-year survival rate to OG patients with curative resection (88.0 and 85.8%, respectively; P=0.547). Female patients in the YG showed a significantly lower survival rate than males in the YG (44.3 and 73.1%, respectively; P=0.0002). Multivariate analyses revealed that macroscopic type, depth of invasion, peritoneal metastasis, distant metastasis and curative resection were independent prognostic factors for the YG with GC. Young GC patients who undergo curative resection do not have a worse prognosis than older patients. Early diagnosis is important in successfully carrying out a curative resection and offering a better prognosis, particularly in females.

Abstract. Thymidine phosphorylase (TP), an enzyme catalyzing the reversible phospholysis of thymidine, deoxyuridine and their analogs at their respective bases and 2-deoxyribose-1-phosphate, thus promoting angiogenesis, is often expressed in macrophages present in tumor stroma. In this study, we investigated whether infiltration of TP-positive macrophages as well as tumor-associated macrophages affected tumor angiogenesis. TP was expressed in human macrophage-like cells, but not in gastric cancer cells in culture. The expression level of TP, the number of infiltrating CD68 + and CD163 + macrophages, and microvessel density (MVD) in the tumor were further analyzed by immunohistochemistry in 111 patients with gastric cancer. Biostatistical analysis of digitized data obtained by image analysis showed that TP expression was significantly correlated with the number of infiltrating macrophages and MVD in intestinal type gastric cancer (p<0.05). The number of infiltrating macrophages was also correlated with MVD in both the intestinal and diffuse types (p<0.05). An increased number of CD68 + macrophages was significantly associated with poor outcome in patients with intestinal type (p<0.001), but not diffuse type cancer. TP could be a specific marker enzyme that is expressed in tumor-infiltrating macrophages, being associated with tumor angiogenesis and poor prognosis in patients with intestinaltype gastric cancer.

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Overexpression of HIF-1α was found to be an indicator of poor prognosis for patients with gastric cancer and was significantly correlated with histology, depth of invasion, VEGF, and MVD.

A careful preoperative endoscopy is necessary for patients who are at high risk of SMGC, and minimally invasive treatment may be indicated in some cases.