In a previous study, the detection rate of SDC2 methylation was 81.1 and 58.2% for CRC and adenoma, respectively, with the specificity of 93.3% (Niu et al., 2017), which was in agreement with our study (Figure 3; Table 4) and other research studies (Wang et al., 2020; Zhao et al., 2020), indicating that the sensitivity of SDC2 for CRC and adenoma had room to be improved. The gene discussed is SDC2; the disease is adenoma.