Compared with those in normal samples, RORB, CALM1, CYP1A1, and CYP1B1 were significantly differentially hypermethylated in multiple cancer types, which was consistent with their transcriptional underexpression (e.g., RORB in COAD, ESCA, and KIRC; CALM1 in COAD and KIRC; CYP1A1 in ESCA; CYP1B1 in ESCA, KIRC, and LUSC). Here, CYP1A1 is linked to cancer.