Figure 1.

Oral Microbiota; Microbiota—metabolites and inflammatory markers in tumors of various sites. Locations are denoted by the following color code. IL: interleukin; SCFA: short-chain fatty acids; ROS: reactive oxygen species; TNF: tumor necrosis factor; CXCL: C-X-C motif chemokine; ↓: decreased level; ↑: increased level. Oral microbiota may be transmitted distally through the bloodstream and digestive tract. Figure 1 shows the changes in oral microbiota, microbial metabolic pathways, microbial metabolites, and inflammation and immune factors when the human body suffers from different kinds of tumors (oral cancer, gastric cancer, colorectal cancer, pancreatic cancer, and lung cancer).