Experimental Detection And Clinical Significance Of Peritoneal Micrometastasis Of Colorectal Cancer Above The Peritoneal Reflection

Objective To compare between Peritoneal lavage cytology(PLC), branched-chain DNA (b-DNA) signal amplification and Semi-quantitative (Sq) RT- PCT in detection of exfoliated cancer cells in peritoneal flushing fluid of colorectal cancer patients during surgery,and to explore the significance of detecting the transcripts of carcinoembryonic antigen (CEA), guanylyl cyclase (GCC) and metastasis-related gene CD44v6 in peritoneal lavages of colorectal cancer patients. Designed to find more specific and sensitive methods and indicators for predicting clinical peritoneal metastasis of colorectal cancerMethods The peritoneal lavages of 48 patients with identified colorectal cancer (colorectal cancer group) and 12 patients with benign colorectal disease (negative control group) were collected. All of the patients were pathologically confirmed. The CEA mRNA in peritoneal flushing fluid were detected by b-DNA and SqRT-PCR. Peritoneal lavage cytology(PLC) was conformed simultaneously to detect the exfoliated cancer cells. To find more sensitive methods to detect the ECC of colorectal cancer. The mRNA level of CEA, GCC and CD44v6 in the collected cells were detected by QuantiGene Reagent System, which is a quantitative RNA detection method based on branched DNA (b-DNA) signal amplification technique.Results In colorectal cacer patient, positive rate of free cancer cells by b-DNA and SqRT-PCR(43.8%, 31.3%), was higher than that by PLC(4.2%). The positive expression rates of CEA, GCC and CD44v6 in the peritoneal lavages were 43.8%(21/48), 60.4%(29/48) and 31.3%(15/48) respectively, and the total positive rate was 72.9%(35/48) in colorectal cancer group, which was more sensitive than that of cytologic examination (2%, 1/48). All 3 marker genes were expressed in human colorectal cancer cell line SW480. There was only 1 sample positive to CEA mRNA in the negative control group. The positive rate of CEA, GCC and CD44v6 expressions were correlated with the Dukes staging, differentiation status, serosal involvement and lymph node metastasis (p<0.05), but not with tumor size, patient age and gender (p >0.05).Conclution Both the b-DNA signal amplification technique-based mRNA detection and SqRT-PCR technologies have advantages and disadvantages to detect free cancer cells in peritoneal flushing fluid, which are effective methods to predict peritoneal micrometastasis of colorectal cancer. but the b-DNA technology operations more simple and less influence factors, the relative quantitative results are more reliable and precisable. Similar to CEA, GCC and CD44v6 may be used as indicators of peritoneal micrometastasis of colorectal cancer. The combined application of these 3 molecular markers will improve the positive detection rate of peritoneal micrometastasis. The detection of CEA, GCC and CD44v6 mRNA in peritoneal lavages is helpful for early diagnosis, prognosis assessment and suitable treatment selection for colorectal carcinoma.