Objective  To explore the significance of the transcripts of carcinoembryonic antigen (CEA)

guanylyl cyclase C (GCC) and metastasis-related gene CD44v6 in peritoneal lavages of colorectal cancer patients.  Methods  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. Human colorectal cancer cell line SW480 were taken as a positive control. The mRNA levels 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. Meanwhile

cytologic examination with microscopy was performed. Results  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 (P0.05)

but not with tumor size

patient age and gender (P0.05). Conclusion  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. Similar to CEA

GCC and CD44v6 may be used as indicators for peritoneal micrometastasis of colorectal cancer. The combined application of these 3 molecular markers will improve the positive detection rate of peritoneal micrometastasis. The b-DNA signal amplification technique-based mRNA detection is more sensitive and specific than that of cytologic examination

and is an effective way to predict peritoneal micrometastasis.