ABSTRACT
<p><b>OBJECTIVE</b>To explore the association between the progression of gastric cancer and the aberrant methylation of CDH1 gene in preoperative abdominal lavage fluid.</p><p><b>METHODS</b>Real-time methylation-specific polymerase chain reaction(qMSP) was used to investigate the methylation status of the CDH1 gene promoter 5'-CpG islands from preoperative abdominal lavage fluid in 92 patients with gastric cancer. The associations between methylation of CDH1 genes and clinicopathologic features and prognosis were investigated.</p><p><b>RESULTS</b>Among the 92 patients with gastric cancer, aberrant methylation of CDH1 gene was detected in 45(48.9%) patients, including total aberrant methylation in 12(13.0%) cases and partly aberrant methylation in 33(35.9%) cases. Significant associations were found between CDH1 methylation status and tumor size, growth pattern, differentiation, lymphovascular invasion, infiltration depth, lymph node metastasis, distant metastasis, and clinical staging(all P<0.05). However, there were no significant associations between CDH1 methylation status with gender, age, tumor location, or Helicobacter pylori infection(all P>0.05). The median progression-free survival was 20 months for CDH1 methylation group and 38 months for non-methylated group, and the difference was statistically significant(P<0.01). Cox model analysis revealed that CDH1 methylation status in preoperative peritoneal lavage fluid was an independent factor associated with postoperative survival in patients with gastric cancer(P=0.000, RR=332.88, 95%CI:21.71-5105.07).</p><p><b>CONCLUSIONS</b>The aberrant methylation of 5'-CpG of CDH1 gene promoter is common in gastric cancer. The examination of CDH1 methylation status of abdominal lavage should be considered in the progression of gastric cancer.</p>