SFRP2 and cancer: When we examined other cancer outcomes, we found that the promoter SFRP2 methylation levels were significantly lower in patients with CRC in late stage (III + IV) than in those in the early stage (I + II) (p = 0.044) (Fig. 1C), and also when compared with healthy participants (p = 0.035) (Supplementary Fig. 1C), with an AUC of 0.879 (95% CI 0.700–0.942) (Fig. 1F, Supplementary Table 1) when adjusted by clinical variables.