PRPH and neoplasm: For diagnostic purposes, we analysed tumour‐specific aberrant DNA methylation with a 4‐gene panel made up of CDH1, PRPH, RASSF1A and DLC1. Methylation at RASSF1A and CDH1 loci has been previously investigated in human lung cancer, either for their clinical pathological significance (Brock et al., 2008; Yu et al., 2015) or for their potential use as tumour biomarkers (Baryshnikova et al., 2008; Han et al., 2009; Hubers et al., 2014a; Hubers et al., 2014b; Hubers et al., 2015).