Sensitivity and Specificity of NGS in Detecting bMSI in Patients With Gastric, Duodenal and Small Intestinal Cancer

Sensitivity and Specificity of NGS in Detecting bMSI in Patients With Gastric, Duodenal and Small Intestinal Cancer

To study the sensitivity and specificity of NGS in detecting Microsatellite State in blood and to evaluate its potential application in gastrointestinal cancer.

NGS can not only detect tissue samples, but also blood samples. For some inoperable cancer patients, the acquisition of tissue samples is difficult and traumatic. It is of great significance for the diagnosis and treatment of these patients to determine MSI status by blood testing. In addition, the heterogeneity of malignant tumors is usually strong, blood testing can overcome the heterogeneity of tissue, and can dynamically monitor the patient's condition. 50 patients with gastric cancer, duodenal cancer and small intestinal cancer will be enrolled in the study. Among them, 30 patients with MSI-H and 20 patients with MSS confirmed by IHC/PCR.The investigators will use 520 gene panel for NGS sequencing of tissue and blood samples from selected patients to study the sensitivity and specificity of NGS in detecting Microsatellite State in blood.

Inclusion Criteria:

• Age (>18 years old).
• Histologically diagnosed as gastric cancer, duodenal cancer or small intestinal cancer (stage III, stage IV).
• The status of dMMR/pMMR was confirmed by IHC/PCR.
• with tissue and blood samples (including ctDNA and white blood cells) that meet the requirements.
• Agree to provide demographic, medical history, pathological diagnosis, imaging diagnosis, TNM staging, ECOG score and other information.

Exclusion Criteria:

• Suffering from other malignant tumors at the same time.
• Others that the investigator consider that is inappropriate for this study.