In this study, mSEPT9 and tumour markers CEA, CA125, and CA19-9 as well as common blood examination indices such as NLR and PLR were analysed to explore the value of single and combined detection of these indices in the early diagnosis of colorectal cancer to provide a reliable clinical basis for the early clinical diagnosis of colorectal cancer. The gene discussed is CEACAM5; the disease is colorectal cancer.