MUC1 and colorectal carcinoma: The subgroup analysis demonstrated that a high level vs. a low level of MUC1 expression (HR = 1.50; 95% CI, 1.29–1.74; P < 0.00001; P = 0.72, I2 = 0%) or a low level vs. a high level of MUC2 expression (HR = 1.56; 95% CI, 1.27–1.92; P < 0.00001; P = 0.11, I2 = 36%) was associated with poor OS in patients with CRC.