Metastatic lymph node ratio in stage III rectal cancer; prognostic significance in addition to the 7th edition of the TNM classification

Abstract

Aims Optimal staging in rectal cancer is indispensable for the decision on further treatment and estimation of prognosis. This study assesses the prognostic capacity of the metastatic lymph node ratio (LNR) in addition to the new TNM classification. Methods LNR was determined, in stage III patients from the Dutch TME-trial. Six year median follow up data from the trial database were used to analyse the relation of LNR to overall survival (OS) and local recurrence (LR). The relation of LNR to lymph node yield was assessed and appropriate cut off values of LNR for clinical use were determined. Results 605 patients were analyzed. 278 underwent pre-operative radiotherapy. 82 patients developed a local recurrence and 289 distant metastases. LNR was an independent risk factor for OS, hazard ratio (HR) 2.10 (95% CI 1.35–3.27) (in addition to age >= 65 years, involved circumferential resection margin (CRM) and new TNM stage) and LR, HR 2.25 (95% CI 1.02–4.56) (in addition to pre-operative radiotherapy and involved CRM). LNR is predictive of OS and LR from a lymph node yield of more than one and more than five respectively. A LNR value of 0.60 offers the best cut off to identify high risk patients (5-years OS was 61 vs. 32%, HR 2.45 (95% CI 1.96–3.08) and 5-years LR rate 12.6 versus 16.3%, HR 1.65 (95% CI 1.03–2.64)). Conclusions LNR is an independent risk factor for OS and LR in addition to the 7th edition of the TNM classification. It can aid in predicting prognosis and identifying patients that should be considered for adjuvant treatment.