The use of phenotype and genotype in the management of pT1 colorectal cancer

Colorectal cancer is one of the leading causes of cancer-related morbidity and mortality in the western world. Early cancers confined to the submucosa (stage pT1) are increasingly being diagnosed in countries with national bowel cancer screening programmes (1). Early cancers are generally associated with excellent outcomes. Many can be effectively treated with local excision, thus avoiding the need for a radical surgical resection and the associated morbidity and mortality. However, studies comparing local excision with major resectional surgery have shown an increased risk of local recurrence after local excision (2). This highlights the need for careful patient selection before the mesorectum is left in-situ. Around 8–14% of early cancers have lymph node metastases and there is a need to accurately identify which cases are likely to benefit from full resection (3-6). A number of high risk features for lymph node metastases are well recognised and routinely reported by pathologists e.g., size greater than 30 mm, poor differentiation, lymphatic invasion, venous invasion, involved resection margin and extension into the lower third of the submucosa. However, reporting of some of these features is subjective and they are often difficult to assess in practice, hence further phenotypic and genotypic biomarkers are required to accurately quantify the risk of nodal disease.