Methylation Analysis of Circulating Tumor DNA in Gastric Cancer

Gastric cancer represents one of the common malignant tumors in China, with high incidence and mortality rates. Surgery is the conventional treatment option for early and intermediate stage gastric cancer, but the diagnosis in the early stage of gastric cancer remains a challenge to clinical practitioners. Circulating tumor DNA (ctDNA) is tumor-derived fragmented DNA with an average size of 166 bp, mixed with cell-free DNA (cfDNA) of other sources in blood circulation. ctDNA is reflecting the most up-to-date status of the tumor genome. Hence, it is considered as a novel biomarker for tumors, which can be qualitative, quantitative, and used for disease monitoring. This study is designed to evaluate the potential clinical utility of circulating tumor DNA (ctDNA) as a clinical index in the diagnosis and prognosis of gastric cancer. The primary purpose of this trial is to describe the profile of ctDNA methylation in gastric cancer. The second purpose is to demonstrate the correlation between the plasma ctDNA methylation status and the diagnosis and prognosis of patients with early and intermediate stage gastric cancer.