The significance as a prognostic biomarker of the top four genes (WFDC1, SFRP1, LGR6 and VWA2) related to the stemness signature was further proven in an independent cohort of 65 ESCC patients using RT-PCR (Fig. 1e, P = 0.031). The gene discussed is SFRP1; the disease is esophageal squamous cell carcinoma.