In China, esophageal cancer is one of the most common cancers, and its incidence and mortality are more than twice the global average. However, most esophageal cancers in China are not detected until they are at moderate and advanced stages with poor prognosis, so early diagnosis and treatment are urgently needed. At present, the role of gut flora in the diagnosis and treatment of esophageal cancer has attracted much attention.

To explore the basic characteristics of gut flora in patients with esophageal squamous cell carcinoma.

From the Fourth Hospital of Hebei Medical University from April to August 2022, 35 patients with esophageal squamous cell carcinoma with no previous anti-cancer treatments were included as esophageal cancer group (EC group), and 35 healthy volunteers as control group. Stool samples of the two groups were collected to detect the gut flora using 16S rDNA sequence. Then an analysis was performed on the Alpha diversity, Beta diversity〔using the principal coordinate analysis (PCoA) 〕 and differential species of gut flora 〔using the linear discriminant analysis Effect Size (LEfSe) 〕 of two groups according to the species annotation of the test results.

The Alpha diversity indices, such as Shannon index, Simpson index, Chao1 index, ACE index and Goods_coverage index demonstrated no significant differences between the two groups (P>0.05), while PCoA graph showed that the Beta diversity differed significantly between the two groups on the whole, and the community structures were different (t=10.837, P<0.001). T-test results showed that there were significant intergroup differences in the abundance of 16 genera at the genus level. Among the top eight genera with relatively high abundance, the abundance of Faecalibacterium, Roseburia and Citrobacter notably decreased, while that of Lactobacillus, Romboutsia, Ruminococcus_torques_group, Intestinibacter and Turicibacter notably increased in EC group (P<0.05). LEfSe analysis showed that two groups had differences in the abundance of 14 different species of gut flora. The abundance of Faecalibacterium and Faecalbacterium-prausnitzii declined significantly, and that of Romboutsia and Romboutsia-ilealis increased significantly in EC group at the genus and species levels (P<0.05) .

Esophageal squamous cell carcinoma patients have significantly differential gut flora, among which Faecalibacterium, Faecalibacterium -prausnitzii, Romboutsia and Romboutsia-ilealis may be specific altered species of esophageal cancer, which are closely related to the occurrence of esophageal cancer.