CDKN2A and cancer: And methylation at the promoter region or non‐coding sequences is often dysregulated in many types of tumour and is associated with tumour initiation, progression, dissemination and metastasis.88 Some detectable ctDNA methylation in cancer patients consists of MLH1, CDKN2A (INK4A), ALX4, CDH4, NGFR, RUNX3, SEPT9, TMEFF289, 90, 91, 92, 93, 94, 95and so on.