Prognostic value of lymph node ratio in stage III colorectal cancer

Aim Recent reports show that a positive metastatic to examined lymph nodes ratio (LNR) has prognostic value in malignancies. This study aimed to evaluate the prognostic value of LNR in patients having resection for stage III colorectal cancer. Method From January 2000 to December 2006, patients who underwent resection for stage III colorectal carcinoma were included. All clinicopathological and follow‐up data were prospectively collected. The impact of LNR and other clinicopathological factors on survival were evaluated. Results The study included 533 (52.3% male) patients with a median age of 70 years. The median number of lymph nodes harvested and the median number of positive lymph nodes examined were 11 and 2, respectively. The median LNR was 0.263 (range, 0.03–1). After a median follow up of 52.65 months, the 5‐year overall survival and disease‐free survival were 55.9% and 49.4%. The patients were stratified into four groups according to LNR quartiles (1, LNR ≤ 0.125; 2, 0.125 < LNR ≤ 0.263; 3, 0.263 < LNR ≤ 0.500; 4, LNR > 0.500). The 5‐year overall and disease‐free survival were 72.8%, 63.1%, 50.0%, 39.6% (P < 0.001) and 68.5%, 54.1%, 47.2%, 29.9% (P < 0.001), respectively, with increasing LNR groups. On multivariate analysis, age, T stage and LNR were independent predictors of both overall and disease‐free survival. Subgroup analysis revealed that the LNR had a prognostic value for disease‐free survival irrespective of number of lymph nodes harvested and location of tumour. Conclusion The LNR is an independent prognostic factor for survival in colorectal cancer and is superior to the pN category in TNM staging.