The ratio of metastatic to examined lymph nodes is a powerful independent prognostic factor in rectal cancer.

Objective: The aim of the study was to evaluate the prognostic value of the ratio of metastatic to examined lymph nodes (LNR) in patients with rectal cancer.
Summary Background Data: Lymph nodes ratio (LNR) has been shown to have prognostic value in patients with colon cancer. The impact of LNR on disease-free and overall survival in patients with rectal cancer is unknown.
Patients and Methods: From 1998 to 2004, 307 patients underwent rectal resection for adenocarcinoma. The relationships between overall and disease-free survival at 3 years and 15 variables, including the presence or absence of metastatic lymph nodes, the total number of lymph nodes examined, and LNR, were analyzed by multivariate analysis. Patients were then assigned to 4 groups based on LNR: LNR = 0 (N0 patients), LNR = 0.01 to 0.07, LNR >0.07 to 0.2, LNR >0.2.
Results: The mean number of lymph nodes examined was 22 +/- 12. In the multivariate analysis, LNR was a significant prognostic factor for both disease-free (P = 0.006) and overall survival (P = 0.0003), whereas the presence or absence of metastatic lymph nodes was not. LNR remained a significant prognostic factor in the 59 patients in whom fewer than 12 lymph nodes were examined (P = 0.0058). According to LNR values, disease-free and overall survival decreased significantly with increasing LNR (P < 0.001).
Conclusions: LNR is the most significant prognostic factor for both overall and disease-free survival in patients with rectal cancer, even in patients with fewer than 12 lymph nodes examined.