MLNR and cancer: NTSR1, NTSR2, GHSR, MLNR, and NMUR1 promoter hypermethylation presented discriminative ROC curve profiles, which clearly differentiate cancer tissues from normal tissues [Area Under Curve (AUC) = 0.6220, 0.5736, 0.8103, 0.6049, and 0.5631, respectively] (Additional File 4: Fig. S2).