Ratio of metastatic lymph nodes is more important for rectal cancer patients treated with preoperative chemoradiotherapy

AIM:To evaluate the predictive value of the lymph node(LN) ratio(LNR,number of metastatic LNs/ examined LNs) for recurrence in patients with rectal cancer and to compare its applicability according to preoperative chemoradiotherapy(PCRT).METHODS:From 2000 to 2009,967 patients with metastatic LNs after curative resection for locally advanced rectal cancer were identified.Patients were categorized according to PCRT(PCRT vs No PCRT).The cut-off LNR was determined based on the p N1 vs p N2 when the recommended number of LNs was harvested.The 5-year recurrence-free survival(RFS) rates using the Kaplan-Meier method were compared according to p/yp N stage and the LNR in each group.RESULTS:Among patients with the same p/yp N stage,the 5-year RFS rate differed according to the LNR.In addition,the 5-year RFS rate was significantly different between p N and LNR groups in patients with No PCRT.In PCRT group,however,only LNR was associated with prognosis.On multivariate analysis,both p N and LNR were significant independent prognostic factors for 5-year RFS in the No PCRT group.In the PCRT group,only LNR category was found to be associated with RFS(HR = 2.36,95%CI:1.31-3.84,and P = 0.001).CONCLUSION:The LNR is an important prognostic predictor of RFS in rectal cancer patients especially treated with PCRT.Current p N categories could not discriminate between prognostic groups of RFS after PCRT.