BACKGROUND: Esophageal cancer (EC) possesses a high degree of malignancy and exhibits poor therapeutic outcomes and prognosis. However, its pathogenesis remains unclear. With the development of macrogene sequencing technology, changes in the intestinal flora have been found to be highly related to the development of EC, although discrepancies and controversies remain in this research area.
MATERIALS AND METHODS: We comprehensively searched the PubMed, EMBASE, and Cochrane's Central Controlled Trials Register and the Scientific Network's database search projects based on systematically reviewed preferred reporting projects and meta-analyses. We used Engauge Digitizer for data extraction and Stata 15.1 for data analysis. In addition, we used the Newcastle-Ottawa Scale for grade grading and forest and funnel plots, sensitivity, and Egger and Beggar tests to evaluate the risk of bias.
RESULTS: This study included 10 studies that assessed stool, tumor, and nontumor esophageal mucosa (gastroscopy and surgical resection) samples from 527 individuals, including 273 patients with EC and 254 healthy control group. We observed remarkable differences in microbial diversity in EC patients compared to healthy controls. The Chao1 index (46.01 vs. 42.67) was significantly increased in EC patients, whereas the Shannon index (14.90 vs. 19.05), ACE (39.24 vs. 58.47), and OTUs(28.93 vs. 70.10) were significantly lower. At the phylum level, the abundance of Bacteroidetes (37.89 vs. 32.77) increased significantly, whereas that of Firmicutes (37.63 vs. 38.72) decreased significantly; the abundance of Clostridium and Verruciformis increased, while that of Actinobacteria and Proteobacteria decreased to varying degrees. The abundance of Bacteroides (8.60 vs. 15.10) and Streptococcaceae (15.08 vs. 27.05) significantly reduced in EC.
CONCLUSIONS: According to our meta-analysis, in patients with EC, the Chao1 index increased, whereas the Shannon and the OTUs decreased. At the phylum level, the abundance of Firmicutes decreased significantly, whereas that of Bacteroidetes and Proteobacteria increased significantly. At the genus/family level, the abundance of Bacteroidaceae, Prevotellaceae and Streptococcaceae decreased significantly, whereas that of Veillonellaceae increased. This meta-analysis identified changes in gut microbiota in patients with EC; however, its conclusions were inconsistent.
