Potential clinical scenarios of tumour budding in colorectal cancer

Tumour budding, defined as single tumour cells or clusters of 4 tumour cells or less detached from the main tumour body, is a wellestablished indicator of aggressive tumour biology in colorectal cancer. As a marker of tumour dissemination, evidence points towards tumour budding as a morphological correlate of epithelialmesenchymal type changes in the tumour microenvironment. Despite many studies in the literature going back decades, tumour budding has not been systematically integrated in colorectal cancer reporting protocols. The recently published proceedings of the International Tumour Budding Consensus Conference (ITBCC) have sparked the systematic implementation of tumour budding in routine reporting of colorectal cancer. Tumour budding may be particularly relevant to patient management in endoscopically resected pT1 colorectal cancer, stage II tumour and pre-operative biopsies. The present review focuses mainly on these three potential clinical scenarios with the aim to provide a concise and updated overview on tumour budding in CRC.