Purpose: The ratio of positive lymph nodes to total retrieved lymph nodes (lymph node ratio, LNR) has been proposed to be the superior prognostic score in colon cancer. This study aimed to validate LNR in a large, multi-centred population, focusing on patients that have undergone adjuvant chemotherapy.
Methods: Analysis of a prospectively collected database (The West of Scotland Colorectal Cancer Managed Clinical Network) with 1,514 patients with colonic cancer identified that had undergone elective curative surgical resection in the 12 hospitals in the West of Scotland from 2000-2004. Variables recorded were as follows: demographics, adjuvant chemotherapy, number of lymph nodes retrieved, lymph node retrieval ≥12, number of positive lymph nodes and LNR. Follow up continued until June 2009. Univariate and multivariate analyses were performed to determine the influence of LNR on overall survival.
Results: In 673 patients (44.5%), ≥12 lymph nodes were retrieved. Patients had a poorer long-term prognosis with increasing age, T stage and N stage. Retrieval of <12 lymph nodes and increasing LNR were both found to be significantly associated with poorer long-term survival, but on multivariable analysis, LNR was the only independently significant variable. In patients that had received adjuvant chemotherapy, only patients staged in the second lowest LNR group (0.05-0.19) had a significant improvement in long-term survival.
Conclusion: Lymph node ratio is the optimal method of assessing lymph node status and highlights the heterogeneity of patients with node positive disease, altering patient stratification with implications for adjuvant chemotherapy.