[Prognostic value of metastatic lymph node ratio in gastric cancer]

To evaluate the value of the metastatic to examined lymph nodes (rN) ratio in gastric cancer patients who underwent radical resection.

In this retrospective study, data were collected from the medical records of 710 patients who underwent radical gastrectomy (R0) for gastric cancer from 1980 to 2006 in the Department of Surgical Oncology at the First Affiliated Hospital of China Medical University. The patients were divided into 2 groups according to the number of examined lymph nodes: Group 1 consisted of 327 patients with <15 examined lymph nodes and Group 2 consisted of 383 patients with ≥15 lymph nodes. rN categories staging and pN categories were divided separately according to the metastatic lymph node ratio and the examined lymph nodes. The prognostic factors were analyzed by univariate (Log-rank) and multivariate (Cox model) analysis methods.

The median survival time was 74 months (95% CI:55.6-92.4 months) in Group 1 and 96 months (95% CI:77.8-119.2 months) in Group 2, and the difference was not statistically significant (P>0.05). On multivariate analysis, the N ratio remained as an independent prognostic factor in both Group 1 (P<0.01, RR=1.225, 95% CI:1.102-1.362) and Group 2 (P<0.01, RR=1.421, 95% CI:1.269-1.592). However, pN stage was an independent prognostic factor only in Group 1. When the rN ratio classification was applied, there were no significant differences between each categories (P>0.05). However, the overall survival of patients with pN1 disease in Group 1 was significantly shorter than that in Group 2 according to the pN stage classification (P<0.01).

The metastatic lymph node ratio is an independent prognostic factor of the prognosis of gastric cancer. The staging system based on metastatic lymph node ratio (rN) is more reliable than the system based on the number of metastatic lymph nodes in the prediction of the prognosis of gastric cancer.