Prognostic impact of lymph node ratio in patients undergoing preoperative chemoradiotherapy followed by curative resection for locally advanced rectal cancer

Background/Aim: To analyze the prognostic significance of nodal status in patients undergoing preoperative chemoradiotherapy (CRT) followed by curative resection for locally advanced rectal cancer. Patients and Methods: Between 2000 and 2015, 80 consecutive patients with rectal cancer underwent preoperative CRT followed by curative resection. The lymph node ratio (LNR) was defined as the number of positive lymph nodes (LNs) divided by the examined LNs, and log odds of positive lymph nodes (LODDS) was the log of the ratio between positive and negative LNs. The prognostic value of these indicators was evaluated in terms of overall (OS) and disease-free (DFS) survival. Results: The median follow-up period for patients overall was 59 months (range=11-190 months). The median number of examined LNs and number of positive LNs were 10 (range=1-29) and 2 (range=1-27), respectively, and the median LNR and LODDS values were 0.0 (range=0.0-0.96) and −1.0 (range=−1.7-1.3), respectively. The 5-year OS and DFS were 83% and 64%, respectively. In multivariate analysis, LNR was an independent prognostic factor in terms OS (p=0.041) but not for DFS (p=0.075). LODDS was not significantly associated with OS or DFS. In patients with clinical stage III rectal cancer, LNR was significantly associated with OS and DFS when the number of evaluated LNs was greater than 12 (p=0.038 for OS, p=0.006 for DFS). Conclusion: Our study suggests that LNR is a more effective prognostic factor than LODDS in terms of predicting survival. LNR was a significant predictor for survival for patients with clinical stage III rectal cancer with >12 harvested LNs.