In subgroup analyses, KRAS mutation detected by cfDNA in pancreatic cancer, colorectal cancer, non-small cell lung cancer and ovarian epithelial cancer had HRs of 2.81 (95% CI 1.83–4.30, P<0.01), 1.67 (95% CI 1.25–2.42, P<0.01), 1.64 (95% CI 1.13–2.39, P = 0.01) and 2.17 (95% 1.12–4.21, p = 0.02) (shown in Fig 4), respectively. This evidence concerns the gene KRAS and colorectal cancer.