Statistical analysis

SPSS statistics (version 22) was used to perform the statistical analysis. Independent t-test was used to compare the mRNA expression level of PTK7 between cancer tissue and non-tumorous mucosa, and two-tailed χ² test was used to compare the expression of PTK7 protein in CRC TMA or adenoma. Two-tailed χ² test or Fisher's exact test were performed to assess the correlation between PTK7 expression and the clinicopathological parameters. Overall survival rates were analyzed by Kaplan-Meier survival tests, and P-value was calculated via log-rank test to evaluate the correlation of the patient prognosis with PTK7 expression or other parameters. Multivariate survival analysis was performed with Cox proportional hazards regression model to identify the independent parameters affecting overall survival. P<0.05 was considered significant.