Detection Of Peritoneal Micrometastasis Of Advanced Gastric Cancer With Omentum Milky Spot

Background and purpose:Gastric cancer is one of the leading cause of mortality in China. Peritoneal dissemination is the most common type of recurrence after surgery in advanced gastric cancer and is one of the reasons for their poor prognosis. Even after curative lymphadenectomy, peritoneal occurs in approximately half of the case. Many studies have indicated that gastric cancer cells selectively infiltrate into the milky spots in the early stage of peritoneal dissemination, and then forms micrometastasis. The objective of this study was to evaluate the clinical impact of greater omentum for detection of peritoneal micrometastasis.Methods:From Aug.2011to Nov.2011,42gastric cancer patients received gastrectomy in Fudan University Shanghai Cancer Center. Besides, we selected3patients with intramucosal carcinoma as negative control and3patients with peritoneal metastasis as positive control. Intraoperative the tissue of lesions adjacent omentum artery and non-vascular area were obtained. CD68expression was detected by immunohistochemistry on greater omentum, then counting the distribution of the milky spots in proximal and distant. Peritoneal lavage cytology was performed and CK20mRNA, MMP-7mRNA in greater omentum was detected by real-time reverse transcriptase-polymerase chain reaction. All patients were followed-up to1year.Results:Milky spots in the proximal was12per square centimeter, much more than that the distal (8per square centimeter)(P=0.000). CK20mRNA, MMP-7mRNA positive rates in greater omentum were40.5%(17/42) and45.2%(19/42), respectively, which were both higher than that of cytological examination16.7%(7/42)(P<0.01). The clinical stage and lymph node metastasis were correlated with the positive rate of PLC, CK20mRNA and MMP-7mRNA (P<0.05).3patients were found to have peritoneal disease after1year, and these patients all positive in greater omentum and all negative in PLC.Conclusions:CK20mRNA, MMP-7mRNA detected by real-time reverse transcriptase-polymerase chain reaction in greater omentum is more sensitive than PLC for peritoneal micrometastasis of advanced gastric cancer. It can be used to conclude the occurrence of peritoneal micrometastasis and provide more reliable evidence in postoperative treatment and prognosis.