Prognostic Value of Lymph Node Ratio in Patients with Resected Synchronous Colorectal Liver Metastases and Less Than 12 Examined Lymph Nodes

Background Recent studies suggest that lymph node ratio (LNR) has significantly better prognostic power than N-status in patients with colorectal cancer, in particular when the number of evaluated lymph nodes (LNs) was insufficient. The aim of this study was to assess the prognostic value of LNR in patients with resected synchronous colorectal liver metastases (SCLMs) and less than 12 examined LNs. Methods A prospectively maintained database of patients with resected SCLMs was queried for patients with less than 12 LNs evaluated at the time of surgery. X-tile software was used to determine the LNR cutoff value able to divide the patients in two subgroups with distinct prognosis. Overall survival (OS) and disease-free survival (DFS) rates were compared by log-rank test. A multivariate Cox regression analysis identified independent prognostic factors. Results A cutoff LNR value of 0.22 divided patients into Low-LNR group (35 patients) and High-LNR group (36 patients). Both OS and DFS rates were significantly higher in Low-LNR group than those in High-LNR group. Independent predictors of poor OS were High-LNR (HR: 2.841, 95% CI: 1.480–5.453, p value = 0.002), bilobar SCLMs (HR: 2.253, 95% CI: 1.144–4.437, p value = 0.019) and lack of adjuvant chemotherapy (HR: 2.702, 95% CI: 1.448–5.043, p value = 0.002), while the only independent predictor of poor DFS was High-LNR (HR: 2.531, 95% CI: 1.259–5.090, p value = 0.009). Conclusions LNR > 0.22 was independently associated with poor OS and DFS in patients with resected SCLMs and less than 12 evaluated LNs.