Significance of Intraperitoneal-free KRT20 and CEACAM6 mRNA Expression for Peritoneal Recurrence of Gastric Cancer

Background/Aim: Peritoneal lavage cytology is widely used to predict peritoneal recurrence after surgery, but cases of peritoneal recurrence are often recognized in patients with peritoneal lavage cytology negativity (CY0) who underwent no residual tumour (R0) surgery. We used peritoneal lavage fluid before and after gastric cancer surgery to detect cytokeratin 20 (KRT20) and carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) mRNA by RT-PCR. Materials and Methods: We collected peritoneal lavage fluid before and after surgery from 58 patients who underwent gastrectomy. RNA was extracted from these samples and RT-PCR was performed. RNA expression was defined as positive and negative in cases with values higher or lower than the median value. We investigated the relationship between mRNA expression and clinicopathological and surgical factors and prognosis. Results: Tumour invasion to the sub-serosa (T3) or penetration of the serosa (T4a), lymph node metastasis, and more than 150 ml intraoperative bleeding were significantly correlated with KRT20 mRNA expression. Multivariate analysis of its relationship with peritoneal recurrence showed that the odds ratio of CEACAM6 mRNA for recurrence was high (odds ratio=24.753; 95%CI=0.883-694.06; p=0.0592). All cases with peritoneal recurrence were CEACAM6-positive at pre- or post-surgery. The prognosis of peritoneal recurrence for both KRT20- and CEACAM6-positive cases was significantly poorer than that of other cases. The recurrence-free survival of the CEACAM6-positive group was significantly poorer than that of the CEACAM6-negative group. Conclusion: Measurement of CEACAM6 mRNA in peritoneal lavage fluid at pre- and post-surgery may be useful as a predictor of peritoneal recurrence.