The Significance Of The Detection On CEA And CK20 Of Gastric Cancer Patients And A Tentative Study On The Application Of Immunosensor

Background Gastric cancer is one of the most common malignant tumors, which takes place so often that it ranks the second in the incidence of various malignant tumors and its death rate ranks first. Metastasis and recurrence are the main causes of death of gastric cancer patients. Although many patients receive the standard D2 radical surgery, they have still died of recurrence and distant metastasis. The traditional clinical staging is the main basis on which treatment is determined, but we often find some patients in very early stages still subject to local recurrence or distant metastasis. The introduction of the concept of micrometastasis of tumor makes people know the tumor from the local body to the whole. The concept that gastric cancer is a systemic disease has been widely recognized. Treatment is not limited to local surgical therapy but systemic whole body treatment based on surgical removal of lesions, attaching emphasis to a comprehensive understanding of disease and paying attention to whether there are micrometastases or not. To take individual monitoring and integrated treatment according to the circumstances of each patient, only by this can we make progress in the treatment of gastric cancer. Therefore, it is of great importance for prognosis and guidance on the comprehensive treatment to determine whether there is the metastatic potential of gastric cancer and early diagnose micrometastasis of gastric cancer.Objective To study the clinical significance for gastric cancer patients of the different methods and different sites of CEA and CK20 detection, and to tentatively investigate clinical value of the electrochemical immunosensor CEA.Methods (1) Make use of the immunohistochemical method to detect CEA and CK20 expression of gastric cancer tissues and analyze it with clinical pathology data. (2) Use real-time fluorescent quantitative reverse transcription polymerase chain reaction(FQ-RT-PCR) to detect on the expression of CK20mRNA and CEAmRNA in free cells in abdominal cavity, lymph nodes and peripheral blood of gastric cancer patients, and to detect the expression of CEA and CK20 in peripheral blood using enzyme linked immunosorbant assay, and make analysis with clinical pathology data and outcomes of follow-ups. (3) Establish CEA electrochemical immunosensor, verify its performance, detect patients with gastric cancer using it, and explore its clinical value.Results (1) CEA has no expression in the control group with chronic gastritis, but high expression in gastric cancer tissues and adjacent tissues. The positive rates were 87.76% and 44.90%. Compared to the control group with chronic gastritis, both of them were significantly higher (P<0.05). There is statistical significance (P<0.05) in the increased expression of adjacent of gastric cancer group and the adjacent group. C20 in gastric cancer group and the adjacent group and control group has different levels of expression, and the positive expression rates were 77.55%,38.78% and 20.00%. The expression of gastric cancer group is higher than the other two groups (P<0.05), and there is no difference between the expression of the adjacent group and the control group. The expression of CEA in gastric cancer tissues is not related with age, gender or lymph node metastasis (P> 0.05), but is related with the degree of cell differentiation, UICC tumor stage and the depth of tumor invasion (P<0.05). (2) The positive rate of peritoneal free cells CEAmRNA is 42.85%, and that of CK20mRNA is 38.78%. There is no positive expression in control group. Compared with the control group, there was statistical significance in the increased expression (P<0.05). The expression of CK20mRNA and CEAmRNA is related to whether there is lymph node metastasis and the depth of tumor invasion (P<0.05), but has nothing to do with the degree of differentiation (P>0.05). The expression of CK20mRNA and CEAmRNA is related with prognosis in patients and the average survival time for positive expression is significantly shorter (P<0.01). (3)The positive expression rates for CK20mRNA and CEAmRNA in lymph nodes of gastric cancer patients in stageⅠandⅡwere 30.69% and 31.77%, and the positive expression rates of CEA and CK20 were 22.38% and 23.10%, which showed significant difference when compared with each other. Prognosis of positive expression is poor. (4) The positive expression rates of CK20mRNA peripheral blood and CEAmRNA gastric cancer group are 65.31% and 57.14%, and there is no positive expression in the control group. Compared with the control group both of them are significantly different (P<0.01). Analyzed from the positive expression rate, the relationship between the expression of CK20mRNA peripheral blood and CEAmRNA and the type of the clinical pathology has exactly the same meaning with the expression of CEA and CK20 in cancer group, while analyzed from gene expression, the expression of CK20mRNA in poorly differentiated tumor is significantly higher, which has statistical difference (P<0.05). (5) Serum CEA and CK20 in the control group were negative and the positive rate of CK20 in patients with gastric cancer is 20.41%. The average of positive group is 2.67±1.21ng/ml; and positive rate of CEA is 51.02%. The average of positive group is 14.46±7.29ng/ml, while the average of negative group is 1.02±0.79ng/ml. Compared with the normal control group the increased positive rate of CEA was statistically significant (P<0.01), while the increased positive rate of CK20 was not significant (P> 0.05). The positive rate of CK20 was significantly lower than the level of blood CK20mRNA, there are statistical significance between the two (P<0.01). When CEAmRNA compared with CEA, the positive expression of them was of no significant difference (P> 0.05). (6) The expressions of peripheral blood CEAmRNA, CK20mRNA, CEA and CK20 are related with prognosis of patients, and the average survival time of the ones with positive expression was significantly shorter (P<0.01). (7) The established CEA immunosensor has good responsiveness, repeatability and reproducibility. Compared with the ELISA method, results of serum samples test has a good correlation (r=0.999), and there is no difference between the sensitivity of detection of CEA. (8) The monitoring of CEA immunosensor for postoperative gastric cancer patients showed that prognosis of patients with CEA being continuous positive and negative turning to positive is poorer than that of patients with CEA being postoperative continuous negative and positive turning to negative (P <0.01). When compared the chemotherapy effective group with the ineffective group, the difference in positive rate of CEA has no statistically significant (P>0.05), but the degree of CEA expression is statistically significant (P<0.01).Conclusions (1) The expression of CEA in gastric cancer increases, and the positive expression is related to tumor stage, differentiation, and depth of invasion; the expression of CK20 in gastric cancer increases, and the positive expression is related to tumor stage and depth of invasion. CEA, CK20 can be used as tumor markers of gastric cancer. (2) The detection of expressions of CK20mRNA and CEAmRNA in peritoneal free cells, lymph nodes and peripheral blood can early diagnose micrometastasis and may guide treatment and evaluate prognosis. The detection of serum CEA also has some value. (3) Peritoneal metastasis is related to tumor invasion and lymph node metastasis and micrometastasis in peripheral blood is related to tissue differentiation, depth of tumor and whether there is lymph node metastasis. (4) CEA immunosensor was successfully constructed and can be used for postoperative monitoring of gastric cancer. CEA continuing to increase after the surgery shows that the prognosis is poor, and the chemotherapy should be adjusted according to CEA results. Regular monitoring of Serum CEA in patients with gastric cancer may Assessment of efficacy, guide treatment and predict prognosis.