Early-onset gastric cancer (EOGC) is a lethal malignancy with a poor prognosis. It differs from late-onset gastric cancer (LOGC) in clinical and molecular characteristics. The current strategies for EOGC detection have certain limitations in diagnostic performance due to the rising trend in EOGC. Hence, identifying novel EOGC bioindicators is crucial.

Due to widespread gastric cancer (GC) detection efforts and timely interventions (removal of precancerous lesions and early-stage GC), the GC-associated mortality rate has declined worldwide. However, epidemiological studies show rising GC incidences among young adults (< 50 years old) without familial or hereditary origin. This illness, known as early-onset GC (EOGC), comprises 20-30% of new GC diagnoses, mainly among individuals aged 30-40 years; the median overall survival time is 11.7 months. Although the underlying cause behind this trend is poorly understood, there is a general understanding that EOGC epidemiologically, biologically, and pathologically differs from late-onset GC (LOGC, ≥ 50 years). Therefore, EOGC patients require clinical assessment and intervention distinct from those applied in LOGC.

Of note, several population-based epidemiological studies have suggested that EOGC patients exhibit significantly different behaviors from LOGC patients. EOGC patients are more likely to have earlier lymph node and distal metastasis than LOGC patients during disease progression. These tough challenges raise clinical concerns: EOGC is more aggressive than LOGC; thus, a delayed diagnosis can severely affect patient survival outcomes. Moreover, the current approaches to GC detection, such as CEA, HP serology, and pepsinogen (PG), are insufficient for detecting early-stage GC and have yet to be investigated in young individuals with EOGC. Accordingly, these limitations strongly underscore the necessity to establish potent alternative indicators that facilitate the timely detection of EOGC.

Inclusion Criteria:

• Having signed informed consent
• 50 years old ≥ Age ≥ 18 years old
• Histologically confirmed gastric adenocarcinoma

Exclusion Criteria:

• Other previous malignancy within 5 year
• Surgery (excluding diagnostic biopsy) within 4 weeks prior to study
• Pregnancy or lactation period
• Legal incapacity

Community Sample Shanxi - Hospital and community sample Beijing -Hospital