Results of subgroup analysis on cancer types showed that a down-regulated p27 protein indicated an unfavorable OS in patients with GC (HR: 1.47, 95% CI: 1.23–1.76, P < 0.0001; Supplementary Figure 2; Table 1) and CRC (HR: 1.81, 95% CI: 1.44–2.27, P < 0.0001; Supplementary Figure 2; Table 1), but not in patients with ESCC (HR: 1.41 95% CI: 0.92–2.14, P = 0.114; Supplementary Figure 2; Table 1). This evidence concerns the gene CDKN1B and esophageal squamous cell carcinoma.