Abstract: Objective To describe and compare the distribution and differences of oral microbiota between gastric cardia carcinoma and healthy controls, and provide clues and insights to explore the etiology of gastric cardia carcinoma (GCC). Methods A total of 33 GCC from October 2015 to January 2016 and 33 healthy controls from August 2017 to January 2018 were enrolled in the study, from Linzhou Cancer Hospital, Henan province. Oral saliva specimens from participants were collected and microbial DNA extraction were conducted. The 16S rRNA V4 region was sequenced by Illumina MiniSeq sequencing platform. Alpha-, beta- diversity and relative abundances were used to compare the differences between GCC and healthy control groups. Results There was a decreased observed Operational Taxonomic Units in GCC compared with the healthy controls (175 vs 198, P < 0.05), while the Shannon index did not show significant difference. The beta diversity was significantly different between two groups (P < 0.001). The relative abundance of Prevotella and Veillonella in the saliva of GCC was significantly higher than those of healthy controls (P < 0.001). Conclusions The oral saliva microbiota of GCC is significantly different from that of healthy controls.

Key words: gastric cardia carcinoma, oral microbiota, 16S rRNA sequencing