Fecal Markers Streptococcus Anginosus and Streptococcus Constellatus for Non-Invasive Screening and Early Warning of Gastric Cancer

Background: Most gastric cancer (GC) patients are diagnosed at an advanced stage, which indicates their poor prognosis. We aimed to investigate novel fecal microbial markers for clinical application in the screening and early diagnosis of gastric cancer (GC). Methods: This is an observational study from three cohorts. In discovery cohort, 16S rRNA gene analysis was performed in paired samples (gastric tissues, feces) from GC and CG patients to determine differential microbes. The relative abundances of the differential microbes were detected using qPCR in training cohort. The diagnostic efficacy of fecal marker Sa/Sc was validated in validation cohort. Findings: 575 gastric cancer (GC) patients, 468 chronic gastritis (CG) patients were enrolled from ten hospitals in China. Significant enrichments of Streptococcus anginosus (Sa) and Streptococcus constellatus (Sc) in both cancerous tissues (P < 0·05) and feces ( P < 0·0001) were observed in patients with intraepithelial neoplasia, early and advanced GC. Either the marker parallel test Sa ∪ Sc or single marker Sa/Sc demonstrated superior sensitivity (Sa: 75·6% vs. 72·1%, P <0·05; Sa: 84·4% vs. 64·0%, P <0·001; Sa∪ Sc: 91·1% vs. 81·4%, P <0·01) in detecting early GC than advanced GC (specificity: Sa : 84.0% vs . 83.9%; Sc: 70.4% vs. 82·3%; Sa ∪ Sc: 64.0% vs. 73·4%). Fecal marker Sa ∪ Sc outperformed Sa ∪CEA/ Sc ∪CEA in the discrimination of advanced GC(sensitivity: 81·4% vs. 74·2%; 81·4% vs. 72·3%, P <0·01; specificity: 73·4% vs. 81·0 %; 73·4% vs. 81·0%). The performance of Sa ∪ Sc in the diagnosis of both early and advanced GC was verified in the validation cohort. For the overall diagnosis of early and advanced GC, Sa ∪ Sc achieved the AUC value of 0·81 with sensitivity of 94·6% and 81·9%, respectively. This study is registered with Clinicaltrials. gov Identifier NCT04638959, the trial has ended and this report represents the final analysis. Interpretation: Fecal Sa and Sc are important signs of early warning in GC and non-invasive, accurate and sensitive fecal markers to detect early and advanced GC. Trial Registration: (Clinicaltrials. gov Identifier NCT04638959). Funding: National Natural Science Foundation of China, Shanghai Municipal Health Commission, Collaborative Innovation Cluster Project, Shanghai Sailing Program and Innovative research team of high-level local universities in Shanghai. Declaration of Interest: The authors declared no competing interests. Ethical Approval: This study was approved by the Ethics Review Committees of all participating hospitals