Systematic review and meta-analysis of histopathological factors influencing the risk of lymph node metastasis in early colorectal cancer

Aim Lymph node (LN) metastases are present in up to 17% of early colorectal cancers (pT1). Identification of associated histopathological factors would enable counselling of patients regarding this risk. Method Pubmed and Embase were employed utilizing the terms ‘early colorectal cancer’, ‘lymph node metastasis’, ‘submucosal invasion’, ‘lymphovascular invasion’, ‘tumour budding’ and ‘histological differentiation’. Analysis was performed using REVIEW MANAGER 5.1. Results Twenty‐three cohort studies including 4510 patients were analysed. There was a significantly higher risk of LN metastasis with a depth of submucosal invasion > 1 mm than with lesser degrees of penetration (OR 3.87, 95% CI 1.50–10.00, P = 0.005). Lymphovascular invasion was significantly associated with LN metastasis (OR 4.81, 95% CI 3.14–7.37, P