Proportional Nodal Burden as a Marker of Recurrence Risk in Non-Metastatic Colorectal Adenocarcinoma: The Prognostic Role of Lymph Node Ratio

Background: Pathological N staging remains central to prognostic assessment in colorectal adenocarcinoma; however, it captures nodal disease as an absolute count and does not account for the total number of examined lymph nodes. The lymph node ratio (LNR) may refine postoperative risk stratification by integrating both metastatic nodal burden and lymph node yield. This study evaluated the prognostic value of LNR in a contemporary surgical cohort of patients with colorectal adenocarcinoma. Methods: This retrospective single-center cohort study included consecutive adult patients who underwent surgery for histopathologically confirmed colorectal adenocarcinoma at the Surgical Oncology Clinic of Ankara Bilkent City Hospital between January 2020 and 25 March 2026. Patients with metastatic disease were excluded from the primary curative-intent analysis. LNR was calculated as the number of metastatic lymph nodes divided by the total number of harvested lymph nodes and categorized as 0, 0.01–0.20, and >0.20. Overall survival (OS) was calculated from the date of histopathological diagnosis, whereas disease-free survival (DFS) was calculated from the date of curative-intent surgery. Survival outcomes were evaluated using Kaplan–Meier analysis and Cox proportional hazards regression. Results: Among 309 screened patients, 274 non-metastatic patients constituted the final analytic cohort. LNR categories were LNR 0 in 159 patients (58.0%), LNR 0.01–0.20 in 76 patients (27.7%), and LNR > 0.20 in 39 patients (14.2%). Median observed follow-up was 24.1 months [IQR, 13.9–35.8] for OS and 22.4 months [IQR, 10.8–34.3] for DFS. During follow-up, 60 deaths and 90 DFS events occurred. Three-year OS was 76.4%, 71.5%, and 53.4% across the three LNR groups, respectively (log-rank p = 0.014), whereas 3-year DFS was 74.7%, 62.4%, and 9.6%, respectively (log-rank p < 0.001). In multivariable analysis, LNR > 0.20 remained independently associated with impaired DFS (adjusted HR 4.84 (95% CI 2.77–8.46); p < 0.001), whereas its association with OS was attenuated after adjustment. Conclusions: In patients undergoing surgery for non-metastatic colorectal adenocarcinoma, LNR > 0.20 identifies a high-risk subgroup with markedly impaired disease-free survival. LNR may complement conventional N staging and improve postoperative recurrence-risk stratification using information already available in routine pathology reports.