Identification of clinical and pathological risk factors for lymph-node metastasis in T1 stage colon cancer: a population-based study.

Accurate preoperative evaluation of lymph-node metastasis (LNM) in patients with pathological T1 (pT1) colon cancer is essential for determining the appropriate extent of colectomy and lymphadenectomy. This study aimed to identify clinical and pathological predictors of LNM and to develop a practical tool for individualized risk assessment. Patients with pT1 colon adenocarcinoma diagnosed between 2010 and 2015 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. After applying exclusion criteria-including distant metastases, multiple primaries, missing key clinical data, and incomplete records-2700 cases were included. LNM status was compared across baseline variables using Chi-square and t tests. Multivariable logistic regression was used to identify independent predictors of LNM, reported as odds ratios (ORs) with 95% confidence intervals (CIs). A nomogram was constructed based on significant variables and validated internally using 1,000 bootstrap resamples. Model performance was evaluated through area under the curve (AUC), calibration, and decision-curve analysis (DCA). Kaplan-Meier methods were used to estimate cancer-specific survival (CSS) and overall survival (OS). LNM was present in 12.8% (n = 345) of cases. Patients with LNM were younger and more likely to present with sigmoid tumors, high-grade histology, perineural invasion, tumor deposits, and surgical delays. On multivariable analysis, factors independently associated with LNM included younger age, Black race (OR 1.55, 95% CI 1.08-2.20), sigmoid location (OR 1.70, 1.30-2.23), higher histological grade, surgical delay beyond 14 days, perineural invasion (OR 4.93, 2.24-10.77), and presence of tumor deposits (OR 4.70, 1.86-11.56). The nomogram demonstrated good discrimination (corrected AUC = 0.664) and calibration, with favorable net benefit at threshold probabilities below 20%. Five-year CSS was modestly lower in the LNM group (94.7 vs. 96.8%, P = 0.019), while OS showed no significant difference (P = 0.36). LNM is not uncommon in pT1 colon cancer. Several clinical and pathological features can help predict LNM risk. The proposed nomogram offers a useful, evidence-based tool to guide surgical decision-making and patient counseling. External validation is needed before routine clinical application.