Accuracy of TNM staging in colorectal cancer: a review of current culprits, the modern role of morphology and stepping-stones for improvements in the molecular era

Abstract

Colorectal cancer (CRC) is the third most common cancer worldwide. Survival is largely stage-dependant, guided by the tumor–node–metastases (TNM) system for TNM assessment. Histopathological evaluation, including assessment of lymph node status, is important for correct TNM staging. However, recent updates in the TNM system have resulted in controversy. A continued debate on definitions resulting in potential up- and downstaging of patients, which may obscure survival data, has led the investigators to investigate other or alternative staging tools. Consequently, additional prognostic factors have been searched for using the regular light microscopy. Among the factors evaluated by histopathology include the evaluation of tumor budding and stromal environment, angiogenesis, as well as involvement of the immune system (including the ‘Immunoscore’). We review the current role of histopathology, controversies in TNM-staging and suggested alternatives to better predict outcome for CRC patients in the era of genomic medicine.

Key Words::

• cancer staging
• colorectal carcinoma
• histopathology
• immunoscore
• tumor–node–metastases

Acknowledgements

We would like to thank Einar G. Gudlaugsson (MD, PhD) at the Department of Pathology, Stavanger University Hospital, for helpful comments in evaluating the manuscript. This paper is in part based on previous work supported by funding from Folke Hermansen Cancer Fund and Mjaaland Cancer Fund (to KS).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.