虽然手术是根治实体肿瘤的最主要手段，但在胃癌，手术后局部复发、腹膜种植转移，是其治疗失败的主要原因，甚至在无淋巴结转移的病人也是如此。近年来人们发现，胃癌根治术后腹腔内常常出现游离癌细胞，其与术后局部复发、腹膜种植转移明显相关，而同时人们证明了结直肠癌行完整系膜切除后，可以降低局部复发率，具体原因不详。我们的前期研究论证了胃背侧系膜近侧段的基本形态和其信封内脂肪结缔组织中存在着散在癌巢，即“第五转移”。由此我们推测，腹腔内游离癌细胞的出现，是癌细胞从系膜的信封里泄露出来所致，既有肿瘤本身突破膜样信封的途径，即原发性癌泄露，也有手术本身破坏了该信封，导致继发性癌泄露的可能。本项目将通过离体研究、动物实验和临床检验，去证明癌泄露的不同类型，各类型癌泄露的源头和机制，及其预后，建立预防癌泄露的技术方法。这一应用基础研究，将为胃癌根治术提供新的手术原则，并具有普遍意义。

Surgical resection is the major radical procedure for the most solid tumors, include advance gastric cancer. However, local regional recurrence and peritoneal metastasis are major reasons which cause treatment failure after radical gastrectomy, even in those patients without lymphatic metastasis. Recent evidence showed that there was free cancer cells (FCC) in the peritoneal cavity induced by surgery, which caused local regional recurrence and peritoneal metastasis, also include those patients without lymphatic metastasis, and the reason is unknown. Our group demonstrated the proximal segment of dorsal mesogastrium (PSDM) morphologically in adult and metastasis V in it. We hypothesis that the primary cancer leak could be appeared when the primary lesion of gastric cancer invaded whole layers of stomach, i.e. T4, and secondary cancer leak could be induced by the broken of mesogastric envelop during radical gastrectomy. The project we applied aim at to prove the hypothesis by experiments in vivo, in vitro, from batch to beds. Reveal of the origin and mechanism of cancer leak will impact on the principle of surgery for advanced gastric cancer, even for all solid tumors.