CD44 and colorectal carcinoma: Multivariable survival analyses identified carcinoembryonic antigen levels (hazard ratio [HR] = 3.056; 95% confidence interval [CI] = 1.354–6.897; P = 0.007), treatment strategy (HR = 0.212; 95% CI = 0.056–0.808; P = 0.023), and CD133+CD44+CD54+ cellular subpopulation of CTCs (HR = 6.459; 95% CI = 1.461–28.558; P = 0.014) as independent prognostic factors for CRC patients with liver metastasis.