Prognostic Value of the Lymph Node Ratio in Rectal Cancer

Abstract

Mehmet Ince, Yavuz Ozdemir, Ahmet Ziya Balta, Kazim Duman, Ergun Yucel, Ilker Sucullu, Mehmet Levhi Akin

Objective: The pathologic staging of rectal cancer is an important prognostic factor. A sufficient number of harvested lymph nodes is necessary for accurate staging. In patients with an insufficient number of dissected lymph nodes, the lymph node ratio (LNR) can be used as a prognostic factor. The aim of this study was to determine the effect of the LNR on the prognosis of patients with rectal cancer. Materials and Methods: A total of 130 patients who had rectal adenocarcinoma and who underwent surgery between 1996 and 2011 were included in this study. Age, gender, serum carcinoembryonic antigen, type of surgery, and pathological features were retrieved retrospectively. Cut-off values for LNR were 1/12, 1/4, and 1/2; patients were stratified into four groups according to this ratio. The relationship between disease-free survival (DFS) and overall survival (OS) and LNR was investigated. Cumulative survival curves were calculated by the Kaplan Meier method, and survival differences between groups were calculated by the log-rank test. Results: The mean number of lymph nodes examined was 11.5±8. In 75 of all patients (57.7%), fewer than 12 lymph nodes were harvested. Seventy-six patients (58.5%) were evaluated as N0, 35 (26.9%) were N1, and 19 (14.6%) were N2. The number of patients in these LNR groups was 87 (66.9%), 13 (10%), 17 (13.1%), and 13 (10%), respectively. The 5-year survival rate was found to be 72.3% in the LNR1 group, 55.6% in the LNR2 group, 44.4% in the LNR3 group, and 22.2% in the LNR4 group. The difference in OS and DFS rates was significant (p<0.001 for both). Conclusion: The LNR for rectal cancer has a prognostic effect on both DFS and OS. Thus, it may be beneficial for adjuvant therapy decisions, especially in patients with an insufficient number of dissected lymph nodes