SPP1 and esophageal squamous cell carcinoma: DFS analysis of the hub genes demonstrated that high mRNA expression levels of SPP1 (HR: 2.3, P=0.00087), SPARC (HR: 1.8, P=0.021), BGN (HR: 2.1, P=0.0036), POSTN (HR: 1.8, P=0.019), and COL1A2 (HR: 1.7, P=0.034) were related to a poor prognosis in ESCC patients (Figure 6).