Statistical analysis

For clinical analyses, cases were divided into two groups using the minimum p-value approach based on LOXL1 expression level. The minimum p-value approach is a comprehensive method to identify the optimal risk separation cut-off point in continuous gene expression measurements for survival analysis in multiple datasets [24]. Associations between the variables were tested with Student's t-test, Chi-squared test (likelihood-ratio test), and Fisher’s exact test. The degree of linearity was estimated by Pearson’s correlation coefficient. Overall survival was estimated using the Kaplan-Meier method, and survival curves were compared using the log-rank test. Univariate and multivariate analyses were performed using the Cox regression model to identify independent variables predictive of overall survival. A two-sided value of P < 0.05 was considered significant. Data analyses were performed using JMP Pro 14 software (SAS Institute, Cary, NC, USA) and R software version 3.1.1 (The R Foundation).