Gastric cancer (GC) is a leading cause of cancer-related death worldwide. Even in patients undergoing curative surgery for non-metastatic disease, postoperative recurrence frequently occurs due to undetected minimal residual disease (MRD). This study aims to establish a highly sensitive and specific liquid biopsy assay using exosomal microRNAs (exo-miRNAs) to detect MRD and predict distant metastasis before clinical recurrence.

Postoperative recurrence in gastric cancer is largely driven by occult micrometastatic disease that remains undetectable by conventional imaging. While circulating tumor DNA (ctDNA) assays have shown utility in MRD detection, their limited sensitivity and tumor-type variability hinder consistent application in gastric cancer.

Exosomal microRNAs (exo-miRNAs), encapsulated within lipid bilayer vesicles, remain stable in circulation and reflect tumor-derived molecular information. This study seeks to develop and validate an exosomal miRNA-based signature capable of detecting minimal residual disease and predicting future distant metastasis after curative gastrectomy.

Study Phases

1. Discovery Phase - Comprehensive small RNA sequencing to identify miRNAs specific to distant metastasis in gastric cancer.
2. Training Phase - RT-qPCR-based quantification of candidate exo-miRNAs in postoperative plasma samples to develop an MRD signature.
3. Validation Phase - Independent cohort testing to evaluate the diagnostic performance, sensitivity, and specificity of the exosomal MRD panel.

Ultimately, the ENLIGHT assay aims to guide postoperative adjuvant chemotherapy by stratifying patients according to MRD status, enabling precision surveillance and early intervention.

Inclusion Criteria:

• Histologically confirmed gastric adenocarcinoma.
• Underwent curative-intent resection (R0).
• Availability of pre- and postoperative plasma samples.
• Documented clinical follow-up data (recurrence/metastasis status).
• Provided written informed consent.

Exclusion Criteria:

• Insufficient plasma volume or RNA quality for exosomal extraction.
• Presence of synchronous or metachronous malignancies.
• Received neoadjuvant chemotherapy without postoperative follow-up.
• Lack of consent or incomplete clinicopathologic data.

Patients who underwent curative-intent gastrectomy for gastric adenocarcinoma, with available pre- and postoperative plasma samples.

Data collected for the study will be made available to others, including de-identified participant data, at publication, via a signed data access agreement and at the discretion of the investigators' approval of the proposed use of such data