Clinical Significance of Detection of Carcinoembryonic Antigen in Peritoneal Fluid by Reverse Transcription-Polymerase Chain Reaction in Patients with Gastric Cancer

ABSTRACT

PURPOSE: Free cancer cells in the peritoneal cavity exfoliated from a tumor are considered to be responsible for peritoneal dissemination in gastric cancer. To detect free cancer cells, a carcinoembryonic antigen (CEA) was introduced to the marker of gastric cancer. The clinical significance of detecting the carcinoembryonic antigen (CEA) mRNA in the peritoneal fluid was evaluated by RT-PCR in patients with gastric cancer. METHODS: In 50 patients with gastric cancer who received a gastrectomy, the peritoneal washing fluids were obtained and the CEA mRNA was detected by RT-PCR and a cytological examination was taken, simultaneously. The results were correlated with the stage and the recurrence of peritoneal seeding. RESULTS: Positive values of CEA mRNA from the peritoneal washing fluids were observed in 24% (12/50) of patients with gastric cancer but of 4% (2/50) showed peritoneal cytology. There were 8 cases of peritoneal seeding in the follow-up and 6 cases of them presented positive CEA mRNA values (50%, 6/12). According to the stage, positive CEA mRNA values from the peritoneal washing fluids were found in 9% (2/21) in stage I, 20% (2/10) in stage II, 33% (5/15) in stage III and 75% (3/4) in stage IV (P=0.030). In the T classification, positive CEA mRNA values were found in 13% (2/15) in T1, 10% (1/10) in T2, 30% (7/23) in T3 and 100% (2/2) in T4 (P=0.031). In the N classification, positive CEA mRNA values were found in 15% (4/26) in N0, 20% (3/15) in N1, 40% (2/5) in N2 and 75% (3/4) in N3 (P=0.055). CONCLUSION: These results suggest that the detection of CEA mRNA by RT-PCR in peritoneal fluid of gastric cancer patients was more sensitive than the peritoneal cytology, and may have a role in selecting patients with a poor prognosis who may benefit from adjuvant therapy.