In this study, we evaluated the number of exfoliated cells by measuring the faecal expression of β-2-microglobulin (B2M) mRNA that is expressed at similar levels in both normal and cancer cells (Dydensborg et al, 2006), and carcinoembryonic antigen (CEA) and E-cadherin (E-cad) mRNAs that are expressed in normal and CRC colonic epithelium (Benchimol et al, 1989; Dorudi et al, 1993). Here, CEACAM5 is linked to cancer.