This study aims to evaluate the use of Next Generation Sequencing (NGS) to detect circulating tumor DNA in gastric cancer patients after gastrectomy

Gastric cancer is the fourth most common cancer in Vietnam with high mortality rate. Patients at early stages undergo radical gastrectomy with curative intent, but the remaining tumor cells, termed as minimal residual disease (MRD), can later cause relapse. Conventional methods to monitor MRD such as imaging and blood tests for biomarkers such as CEA are not sensitive and specific enough. ctDNA has recently emerged as a promising noninvasive marker with high accuracy to monitor MRD and detect relapse in many cancers such as breast and colorectal cancers. However, its application in gastric cancer has not been extensively evaluated. Therefore, this study aims to use advanced NGS technologies to detect ctDNA in liquid biopsy as a biomarker to monitor MRD after radical gastrectomy.

Inclusion Criteria:

1. Male or Female patients aged 18 years and older
2. Histologically proven primary gastric adenocarcinoma before surgery
3. Clinical stage is locally advanced cT2-4a any N and M0
4. In initial evaluation, patient can undergo radical gastrectomy and lymphadenectomy
5. No preoperative therapy, including chemotherapy and radiotherapy
6. No known cancer diagnosis within last five years
7. Signed informed consent

Exclusion Criteria:

1. Gastrectomy cannot be achieved during operation due to metastasis
2. Patient fails to follow-up and provide postoperative samples

Patients with newly diagnosed and untreated gastric adenocarcinoma