SEPTIN9 and cancer: Most of the currently marketed blood‐based cancer detection products use cfDNA methylation markers, with fluorescence PCR as the detection technology, such as RNF180/Septin9 gene methylation for gastric cancer detection, Septin9 gene methylation for colorectal cancer detection, and SHOX2/RASSF1A/PTGER4 gene methylation for lung cancer detection [17, 18, 19].