In their analysis of 105 pair-matched CRC tumour and ‘normal’ epithelium tissue specimens, Wu et al., previously correlated increased miR-21 expression with advanced CRC staging, lymph node metastases, local invasion, and increased serum carcinoembryonic antigen (CEA) levels through inhibition of the PTEN tumour suppressor gene [56]. This evidence concerns the gene CEACAM5 and neoplasm.