The levels of SYT13 and CEA mRNAs in peritoneal lavages predict the peritoneal recurrence of gastric cancer

Background Although peritoneal lavage cytology often serves as a sensitive method to detect free cancer cells in the abdominal cavity, some patients experience peritoneal recurrence despite negative cytology. The aim of this study was to evaluate mRNAs in peritoneal lavage fluid as potential markers for predicting the peritoneal recurrence of gastric cancer (GC). Methods Peritoneal lavage fluid samples were obtained during surgery conducted on 187 patients with GC and from 30 patients with non-malignant disease (controls). The mRNA levels of nine candidate markers were quantified, and analysis of a receiver-operating characteristic curve compared their accuracies. The cutoff was defined as the highest value of the controls. Results Synaptotagmin XIII (SYT13) and carcinoembryonic antigen (CEA) mRNA levels were analyzed further. SYT13 levels were significantly associated with shorter peritoneal recurrence-free survival (PRFS) and overall survival. Among patients with negative peritoneal lavage cytology, those positive for either SYT13 or CEA mRNA experienced significantly shorter peritoneal recurrence-free survival compared with those with negative fluid (hazards ratio [HR] 4.21, P = 0.0114; HR 3.53; P = 0.0426, respectively). Univariate analysis revealed that SYT13 and CEA mRNA levels were significant predictors of peritoneal recurrence. Positive levels of both SYT13 and CEA mRNA demonstrated the highest HR for peritoneal recurrence (HR 12.27, P = 0.0064). Multivariable analysis revealed that SYT13 positivity was a significant independent prognostic factor (HR 3.69; 95% confidence interval, 1.18-12.74; P = 0.0246). Conclusions Combined measurement of SYT13 and CEA mRNA levels in peritoneal lavage fluid could serve as a promising approach to predict peritoneal recurrence of GC.