Development of a prognostic model based on positive lymph node ratio for yp stage III colorectal cancer.

For locally advanced rectal cancer and potentially resectable T4bM0 colon cancer, neoadjuvant therapy improves remission rates and resectability. However, conventional TNM staging often fails to predict prognosis in ypIII CRC patient's post-neoadjuvant therapy due to lymph node regression (particularly when < 12 nodes are detected). We evaluated the prognostic value of positive lymph node ratio (LNR) in this cohort.Retrospective analysis of 489 ypIII CRC patients treated with neoadjuvant therapy and radical surgery (2008-2018). Optimal LNR cutoff for disease-free survival (DFS) was determined using R software. Patients were stratified into low/high-LNR groups. Clinicopathological characteristics and DFS were compared. A COX regression-based nomogram incorporating LNR was developed and externally validated against TNM staging via ROC analysis.LNR optimal threshold was 0.29 (low: ≤ 0.29, n = 317; high: > 0.29, n = 172). High LNR predicted shorter DFS (HR = 2.103, 95% CI 1.582-2.796, P < 0.0001) and was an independent prognostic factor (multivariate HR = 1.825, 95% CI 1.391-2.394, P < 0.001). The LNR-integrated nomogram outperformed TNM staging in predicting DFS (AUC: 0.852 versus 0.781, P < 0.05).LNR is an independent prognostic factor for ypIII CRC. Supplementing TNM staging with LNR enhances prognostic accuracy.