| Objective: The morbidity and mortality of gastric cancer are the highest in all malignant tumors in China. Most patients of gastric cancer receive a curative resection when they come to hospital. However, seventy to eighty percent of them will still die in the following 5 years. The potential micro- metastases and disseminated tumor cells, which existed in lymph nodes, peripheral blood and bone marrow before operation, are the main cause of recurrence and metastasis. So, if we can find a method to effectively detect and treat these micrometastases before or nearly after operation, our principle to the diagnosis and treatment of gastric cancer would be changed greatly. Additionally, the detection of micrometastasis can monitor the effects of systemic treatment, offer theoretic base for the selection of therapeutic program, and eventually give individualized treatment to every patient. In recent years, the subjects of molecular biology, cell biology and immunology, together with research techniques of these subjects, developed quickly, we can possibly detect very few, or even single tumor cells from many normal cells now. Accordingly, many domestic and foreign researchers have detected tumor micrometastasis by means of new-emerged techniques, such as immunocytochemistry, flow cytometry (FCM) and polymerase chain reaction (PCR), etc. From those reports, we have got some new viewpoints on pathogenesis of gastric cancer. For example, many patients with gastric cancer at very early stage have local or even systemic micrometastasis. In advanced gastric cancer, most patients have tumor cells widespread in their peripheral blood and bone marrow. The number of disseminated tumor cell in bone marrow closely correlated with the patient's prognosis. However, all domestic and foreign researches at precent didn't investigate the micrometastasis of gastric cancer systemically. Some reports selected improper patients; some reports hadn't employed advanced techniques; some reports got their results only by one or two techniques didn't prove them by other techniques. So many results and conclusions are very different from one paper to another. In order to elucidate the status of micrometastasis might exist in lymph nodes, peripheral blood and bone marrow of gastric cancer, and the correlation between those micrometastases and clinopathological variables and prognosis, we employed immunohistochemistry, reverse transcript PCR (RT-PCR), immunofluorescant FCM, immunofluorescent staining and magnetic activated cell sorting (MACS) to systemically investigate the status of micrometastasis in lymph nodes, peripheral blood, and bone marrow of gastric cancer. Then we analyzed the correlation between micrometastasis and clinopathological variables. Finally, the characteristic of morphology, culture and immunohisto- chemistry of disseminated tumor cells in bone marrow of gastric cancer after enriched by MACS were investigated, with the aim to clarify the mechanism of micrometastasis in gastric cancer, and to evaluate the clinical application of micrometastasis in gastric cancer further.Methods1. We investigated 466 lymph nodes obtained from 44 gastric cancer patients operated between April, 1991 and April, 1994. All these lymph nodes showed no metastasis by routine histological examination. Immunohisto- chemical staining SP test was performed on all the samples by monoclonal antibodies of mouse anti-human cytokeratin (CK) 20, mouse anti-human epithelial membrane antigen (EMA) and mouse anti-human CA72-4, respectively. Then, micrometastasis was identified under microscope according to the color of the cells. The results were analyzed with clinical, pathological and follow-up data. 2. Bone marrow and peripheral blood of 49 patients with gastric cancer, 5 patients with benign gastric lesion and 5 healthy volunteers were investigated in this chapter. Expression of CK20 mRNA in those samples was measured by RT-PCR with β2 microglobulin (β2MG) gene as an internal control. The results were analyzed with clinopathological data. At the...
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