ASCEND-Gastric is a prospective, multi-omics, observational study aimed at detecting gastric cancer by combined assays for serum protein markers, deep sequencing of cell-free DNA (cfDNA), circulating tumor DNA (ctDNA) mutation and circulating RNA. The study will enroll 498 participants, including 128 patients with benign gastric diseases and 370 patients with gastric cancer.

Inclusion Criteria for Cancer Arm Participants:

• Age 40-75 years at the day of consenting to the study.
• Able to provide a written informed consent.
• No prior cancer treatment (local or systematic) with either of the following:

A. Pathologically confirmed cancer diagnosis within 42 days prior to blood draw.

B. High suspicious for cancer diagnosis by imaging tests or other routine clinical examinations, with confirmed pathological cancer diagnosis within 42 days after the blood draw.

Exclusion Criteria for Cancer Arm Participants:

• Insufficient qualified blood samples.
• During pregnancy or lactation.
• Recipient of organ transplant or prior non-autologous (allogeneic) bone marrow or stem cell transplant.
• Recipient of blood transfusion within 7 days prior to blood draw.
• Recipient of anti-tumor drugs to treat non-cancer diseases within 30 days prior to blood draw.
• With other known malignant tumors or multiple primary tumors.

Inclusion Criteria for Benign Disease Arm Participants:

• Age 40-75 years at the day of consenting to the study.
• Able to provide a written informed consent.
• Able to provide sufficient and qualified blood samples for study tests.
• Have either of the following:

A. Pathological confirmed diagnosis of benign diseases within 90 days prior to the study blood draw, with no prior treatment such as surgical resection.

B. High suspicious for benign diseases diagnosis by radiological or other routine clinical assessments, with confirmed benign diseases diagnosis within 42 days after study blood draw.

Exclusion Criteria for Benign Disease Arm Participants:

• Insufficient qualified blood sample for study test.
• During pregnancy or lactation.
• Recipient of organ transplant or prior non-autologous (allogeneic) bone marrow or stem cell transplant.
• Recipient of blood transfusion within 7 days prior to study blood draw.
• Recipient of anti-tumor drugs to treat non-cancer diseases within 30 days prior to blood draw.

Eligible participants in cancer arm will be recruited with new diagnosis of gastric cancer and without any types of tumor treatment.

Eligible participants in benign disease arm will be recruited with new diagnosis of benign gastric disease and without any types of treatment.