Further, in a univariate Cox regression analysis in ESCC patients, the poor overall survival correlated with depth of invasion (HR 1.740, P = 0.033), regional lymph node metastasis (HR 1.910, P = 0.015), TNM stage (HR 1.842, P = 0.018) and USP9X expression (HR 2.192, P = 0.002). Here, USP9X is linked to metastatic malignant neoplasm in the lymph nodes.