FFAR4 and esophageal squamous cell carcinoma: To be specific, 4 out of the crucial 13 genes (FFAR4, HTR2A, RASA3, and SH3KBP1) were risk factors of ESCC patients, while the other 8 genes (CD38, CLEC6A, DPP4, STX11, TRAV26-2, TRBV4-2, TRBV5-3, and XCR1) are protective factors.