For different types of digestive system cancers, our research showed that high expression of KLF4 was associated with a significantly prolonged OS in GC (HR = 0.64, 95% CI: 0.49–0.84, P = 0.001) (Fig. 4C) but not statistically significant in CRC (HR = 1.04, 95% CI: 0.61–1.76) (Fig. 4D), PDAC (HR = 1.18, 95% CI: 0.28–4.87) (Fig. 4E) or HCC for OS (HR = 2.37, 95% CI: 0.29–19.20, P = 0.42) (Fig. 4F). This evidence concerns the gene KLF4 and hepatocellular carcinoma.