Detection Of Exfoliated Cancer Cells In Peritoneal Cavity Of Patients With Gastric Cancer And Its Correlation With Overexpression Of C-erbB-2 Protein

Objective To evaluate the significance of detecting exfoliated cancer cells(ECC) in peritoneal washings of gastric cancer by immunocytochemical(ICC) method using CK20 and CEA monoclonal antibodies (Mab) and to investigate the correlation between the presence of cancer cells with operation and overexpression of C-erbB-2 protein. Methods In 30 patients with gastric tumor resection ,the abdomen(close to tumor) was irrigated with 100ml saline solution at a temperature of 37 C immediately after laparotomy and after tumor resection. Subsequently, the peritoneal washings were collected and centrifugated. Samples before tumor resection were detected by conventional cytology method and ICC method using CK20 and CEA monoclonal antibodies. Samples after tumor resection were detected by cytology method and ICC method using CEAMab. Tumor tissue preparations were stained with Mabs for CK20, CEA and C-erbB-2. Lavages of 10 patients with benign disease who underwent laparotomy served as controls. Results Immunocytochemical detection was superior to conventional lavage cytology with the positive rate 43.3%( 13/30) and 23.3%(7/30) respectively (P=0.031). None of 10 patients with benign disease was positive. All positive cytological results were proved positive by ICC. In the two markers, CK20 was more sensitivity. Out of 13 positive peritoneal cavity lavages, 12 of the samples reacted with CK20 Mab and 10 with CEA Mab. The rate of positive detection by immunocytochemical assay was significantly correlated to invasion of serosa, the area of serosa invasion, the differentiation degree and lymph node metastasis (p<0.05), and also with PTNM classification (p<0.01). The positive case immunoassayed by CEAMab was 10 before tumor resection while it was 16 after tumorresection. In stage III+IV and bleeding over 200ml,the detection rate of ECC after tumor resection was significantly higher then before tumor resection. Eleven of 30 cases (36.7%) were positive in expression of C-erbB-2. The positive rate of ECC in patients with C-erbB-2 expression (75.7%) were significantly higher then those without C-erbB-2 expression (26.3%). The overexpression of C-erbB-2 was also related to the stage of cancer and lymph node metastasis, p<0.05. Conclusion Immunocytochemical stain using CK20Mab and CEAMab is a more sensitive and specific method for the detection of microscopically disseminated cancer cells in gastric cancer than conventional cytology. The operation can result in tumor dissemination and it is necessary to improve the operation technical against tumor dissemination by operator. C-erbB-2 gene may play a role in the peritoneal metastasis of gastric cancer and it also can be helpful to the judgement of prognosis of gastric cancer.