局部复发是进展期胃癌行治愈性切除术后预后不良的主要原因。目前认为与术中胃周淋巴结清扫不规范或不彻底有关，但对于那些病理证实无淋巴结转移的胃癌患者(T2N0M0,T3N0M0)术后5年仍有10%-30%的局部复发率，显然这种解释还不够。已有文献和我们现有的临床病理研究均发现在胃癌患者的胃周系膜中存在着孤立的转移癌结节，这些癌细胞与原发灶、淋巴转移和血管转移并无连续性关系。我们认为这是胃癌四大转移途径外的另一类转移途径，鉴于文献中命名繁多，统称为胃周系膜内转移（第Ⅴ转移）。这类转移很可能是胃癌术后局部复发的重要原因。本课题将主要以临床胃癌系膜标本和胃癌细胞系为研究对象，证实胃癌第Ⅴ转移的存在，解剖学基础及转移规律；初步探讨并阐明第Ⅴ转移的分子调控机制。本研究将解释传统胃癌根治术后局部复发的主要原因，为降低胃癌局部复发提供新的理论依据和新的手术根治原则，为降低胃癌局部复发提供可能治疗靶点。

Local-regional recurrence is the main reason for the poor prognosis in advanced gastric cancer after curative radical gastrectomy, which is believed to related with non-standard or halfway lymphadenectomy during gastrectomy. However, the local-regional recurrence rate is still about 10%-30% after surgery in 5 years even in the patients without lymphatic metastasis (T2N0M0, T3N0M0). Recent literature and our clinicopathological research indicated that isolated cancer cells, separate from the primary lesion and lymph nodes, existed in the mesogastrium of resected gastric cancer specimens,leading to the hypothesis that these cancer cells may have infiltrated the mesogastrium through a fifth metastasis route (here named Metastasis V) which is distinct from the other four classic metastasis routes. Local-regional recurrence might be closely associated with these cancer cells in the mesogastrium. Our project aims to: 1. prove the existence of Metastasis Ⅴ, explore the anatomic basis and pattern of Metastasis Ⅴ. 2. elucidate the molecular mechanisms of Metastasis Ⅴ. Overall, our research will clarify the anatomic basis,pathological features and molecular mechanisms of Metastasis Ⅴ in gastric cancer, which will provide new theoretical basis and surgical principle for reducing the local-recurrence of gastric cancer.