Assessment of SOX17 DNA methylation in cell free DNA from patients with operable gastric cancer. Association with prognostic variables and survival.

BACKGROUND: DNA methylation represents one of the most common epigenetic changes in human cancer providing important information regarding carcinogenesis. A possible role as a prognostic indicator has also been proposed. The aim of our study was to evaluate the prognostic significance of SOX17 promoter methylation status in patients with operable gastric cancer. METHODS: Using methylation-specific PCR (MSP) we examined the incidence and prognostic significance of SOX17 methylation status in cell free circulating DNA in the serum of 73 patients with operable gastric cancer. Fifty-one patients were male (69.9%), their median age was 65 years, 43 patients (58.9%) had regional lymph node involvement and all had a Performance Status (WHO) of 0-1. RESULTS: SOX17 promoter was found to be methylated in 43 out of 73 gastric cancer serum samples examined (58.9%). All 20 control serum samples from healthy individuals were negative. Overall survival (OS) was found to be significantly associated with SOX17 methylation (p=0.049). A significant correlation between methylation status and differentiation (p=0.031) was also observed. No other significant associations between different tumor parameters examined and SOX17 methylation status were observed. CONCLUSIONS: SOX17 promoter methylation in cell free DNA of patients with operable gastric cancer is a frequent event and may provide important information regarding prognosis in this group of patients.