SPP1 and esophageal squamous cell carcinoma: We divided 162 ESCC patients from the discovery and validation groups into different clinical subgroups according to different variables and tried to explore the levels and the AUCs of anti-SPP1 autoantibody in different subgroups of ESCC, including age, sex, smoking, drinking, differentiation, TNM stage, lymphatic metastasis, distance metastasis and family tumor history.