In the stratified analyses according to cancer type, expression loss of KLF4 yielded a poorer OS in CRC (HR = 1.17, 95% CI: 1.01–1.37), GC (HR = 1.97, 95% CI: 1.36–2.83, P = 0.015), HCC (HR = 2.30, 95% CI: 1.35–3.92, P = 0.001), and PDAC (HR = 2.70, 95% CI: 1.75–4.17) and a worse DFS/RFS/MFS in CRC (HR = 1.83, 95% CI: 1.14–2.94), HCC (HR = 2.20, 95% CI: 1.43–3.39), GC (HR = 2.14, 95% CI: 1.04–4.41), and PDAC (HR = 2.60, 95% CI: 1.02–6.63), but not statistically significant in ESCC for OS (HR = 0.84, 95% CI: 0.58–1.22). The gene discussed is KLF4; the disease is cancer.