CDKN2A and neoplasm: A hybrid approach to tumour-informed ctDNA sequencing was adopted, whereby a targeted panel of 9 genes (TP53, NOTCH1, PIK3CA, KMT2D, CDKN2A, CASP8, NSD1, FAT1 and FBXW7) made up of the most frequently occurring gene variants in tumour samples was used to sequence baseline plasma cell-free DNA samples.