| Background:Gastric cancer is a common malignant oncoma,of which the annual mortality locates the first place in all kinds of malignant tumor.Many sufferers die of recurrence even after radical operation,because micrometastasises occer. Micrometastasis is microscopic residual tumor cell detected in tissue,body fluid and corpuscular transplant.It exists out of primary affection and can not be detected by routine clinical pathological methods.Current researches consider that,generally speaking,clinical metastasis is developed from micrometastasis.Recently,the rapid development of histochemistry and molecular biological technique promotes the development of micrometastasis.Accompanied by the development and application of immunohistochemistry and reverse transcription-polymerase chain reaction(RT-PCR), it is possible for gastric micrometastasis to be detected,and the realm of the detection of micrometastasis is increasingly attracting attention.The most common recurrence of advanced gastric cancer is peritoneum metastasis.At present,there are many reports about detecting peritoneum micrometastasis.Peritoneal lavage cytology(PLC)is the most popular and important method to detect exfoliated cancer cells(ECC)in abdominal cavity and to prognose peritoneum micrometastasis.However,PLC also has its disadvantage that it has a low sensitivity about detecting small volume cancer cell.It has a higher rate of missed diagnosis,for its positive rate is only 14 to 21 percent.Objective:In the present study,peritoneum biopsy was undertaken intraoperatively, cytokeratin(CK)19,CK20 immunohistochemistry staining were performed on the tissue from biopsy,in order to investigate the condition of peritoneum metastasis in gastric cancer.We aimed to detect the factors and rules of peritoneum micrometastasis, accordingly,to accurately determine the clinical staging of patients suffering from gastric carcinoma.It would provide more reliable evidence in postoperative treatment and prognosis.Materials and methods:Obeject:30 cases of gastric cancer that were operated in department of general surgery,Qilu Hospital of Shandong University were studied from June to October, 2007.In these patients,21 cases were male,while 9 were female,from 38 to 73 years old.Methods:1.Biopsy:Peritoneal washings of these patients with gastric cancer were collected to undertake PLC.A small quantity of transverse mesocolon biopsy was undertaken intraoperatively,CK19,CK20 immunohistochemistry staining were performed on the tissue from biopsy,compared with HE staining and PLC.Lymph nodes were divided into groups conventionally and sent to pathologic analysis with excisional specimen.2.Immunohistochemistry staining:The tissues were solidified by 10%formalin and embed by paraffin.Each paraffin block was cut into 4 slices with 4μm in thickness.2 slices were used for HE staining,1 for CK19 staining,and 1 for CK20 staining.The CK19,CK20 monoclone antibody,PV9000 kits and DAB developer were all purchased from Zhongshan Company,Beijing.3.Microscopic view:CK expresses in epithelial cell.The positive reacting substance expresses in cytoplasm,presenting buffy.We considered micrometastasis had taken place if CK19 or CK20 showed positive while HE staining showed a negative result.4.Statistical Analysis:All of data was analyzed with SPSS10.0 statistics software.The relationship between the depth of invasion,lymph nodes metastasis and peritoneum micrometastasis was tested byχ~2 test.P＜0.05 is regarded as statistical significance.Results:1.There was no positive result of HE staining in all of the 30 paraffin blocks, which demonstrated that the specimens had no metastasis that could be detected by routine methods.It was considered that metastasis occurred when the result of immunohistochemistry staining was positive.2.The positive rate of CK19,CK20 and PLC was 43.3%,30.0%and 10.0%.The difference between CK19 and PLC was statistically significant,so was the difference between CK20 and PLC.3.In the 30 cases we studied,there were 9 cases that serous membrane was broken through,among them,micrometastasis happened in 8 cases.In other 21 cases that serous membrane was not broken through,only 9 cases suffered micrometastasis. The difference between them was statistically significant.Conclusions:1.Compared with conventional PLC,CK19 and CK20 are more sensitive index for detecting gastric cancer micrometastasis.2.Tumor breaking through serous membrane is apt to induce micrometastasis.3.In the study,56.7%of the patients who suffered from gastric cancer were subjected to transverse mesocolon micrometastasis.From this,we can see that it is necessary to remove transverse mesocolon in gastric operation.
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