ObjectiveTo systematically evaluate the effect of mucin 1 (MUC1) expression on the prognosis and clinicopathologic characteristics of patients with colorectal cancer.MethodsThe cohort studies on the relationship between MUC1 expression and the prognosis of colorectal cancer patients were retrieved from PubMed, Embase, Web of Science, Cochrane Library, CNKI, China Biology Medicine, WanFang, VIP, and other databases from the establishment of the database to December 2020. The two researchers screened the literatures according to the inclusion and exclusion criteria, extracted relevant data, and performed meta analysis using Stata 12.0 software.ResultsA total of 17 eligible studies comprising 2 516 patients with colorectal cancer were included. The results of meta-analysis showed that the overall survival (OS) of patients with high MUC1 expression was worse than that with low MUC1 expression [HR=1.51, 95%CI (1.33, 1.71), P<0.001], but not statistically significant with disease-free survival [HR=1.39, 95%CI (0.41, 4.68), P=0.565]. Subgroup analysis results showed the same results as the overall analysis regardless of analysis method (multivariate or survival curve), different ethnic groups (Asian or Caucasian), and different sample sizes (≥100 or <100). The results of clinicopathologic analysis showed that the high expression of MUC1 was correlated with lymph node metastasis, distant metastasis, depth of invasion, and TNM stage (P<0.05), but not correlated with gender, age, degree of tumor differentiation, and tumor location (P>0.05).ConclusionsHigh expression of MUC1 is closely associated with poor prognosis, lymph node metastasis, distant metastasis, tumor invasion depth, and TNM stage in patients with colorectal cancer, which is expected to be an important reference indicator for disease monitoring and prognosis judgment of colorectal cancer.