T1 colorectal cancer: determinants of lymph node metastasis, survival patterns, and risk-adapted management

T1 colorectal cancer presents a management challenge because a minority of lesions harbour lymph node metastasis (LNM), while T1N-positive disease may demonstrate favourable survival compared with some locally advanced node-negative tumours. This narrative review examines determinants of nodal metastasis in T1 colorectal cancer and considers how these features may inform risk-adapted management. This narrative review was conducted across two databases (MEDLINE and Embase), prioritising studies that used standardised definitions, including International Tumour Budding Consensus Conference (ITBCC) criteria for tumour budding and D2-40 or elastin staining for lymphovascular invasion. The most consistent predictors of lymph node metastasis are lymphovascular invasion and high-grade tumour budding, with poor differentiation and submucosal invasion depth adding to risk. Non-granular pseudo-depressed lateral spreading tumours and depressed lesions appear to signal covert submucosal invasion, indirectly increasing nodal risk. Evidence for tumour site, sex, molecular subtype, and lymphatic vessel distribution remains inconsistent or exploratory. Survival for T1N-positive disease is generally favourable compared with high-risk stage II disease, although comparisons are confounded by nodal burden, stage migration, treatment era, and adjuvant chemotherapy. A structured pathology report incorporating lymphovascular invasion, tumour budding, grade, depth, margin status, and morphology may support balanced decisions regarding completion surgery and adjuvant therapy while avoiding overtreatment.