High Ki67 expression is an independent good prognostic marker in colorectal cancer

Aims To correlate Ki67 expression with outcome in colorectal cancer (CRC). Methods Ki67 labelling index (Ki67LI) was analysed by immunohistochemistry on a tissue microarray containing 1800 CRCs. The results were compared with clinicopathological and molecular parameters. Results Ki67LI was considered low in 26.3%, moderate in 56.7% and high in 17.0% of 1653 interpretable CRCs. High Ki67 expression was associated with low tumour stage (p<0.0001) and nodal status (p=0.0315), but not with tumour grade (p=0.8639), histological tumour type (p=0.1542) or tumour localisation, and was an independent prognosticator of favourable survival (p=0.0121). High Ki67 expression was also significantly associated with high-level nuclear beta-catenin and p53 expression (p<0.0001 and p=0.0095, respectively). Conclusions In summary, our data show that high Ki67 expression in CRCs is associated with good clinical outcome. Ki67, p53 and beta-catenin overexpression seem to be linked to CRC, and indicate a cellular state of high proliferative activity. Finally, our findings strongly argue for a clinical utility of Ki67 immunostaining as an independent prognostic biomarker in CRC.