Serum DKK‐1 and DKK‐1 autoantibodies were measured by enzyme‐linked immunosorbent assay in a training cohort (185 ESCC samples vs. 97 normal controls) and validated in a validation cohort (104 ESCC samples vs. 53 normal controls). The gene discussed is DKK1; the disease is esophageal squamous cell carcinoma.