A novel lymph node staging system for gastric cancer including modified Union for cancer Control/American Joint Committee on cancer and Japanese Gastric Cancer Association criteria

Background The TNM system of the International Union for Cancer Control/American Joint Committee on Cancer (UICC/AJCC) and the Japanese Gastric Cancer Association (JGCA) systems are the most used lymph node (LN) staging systems in gastric cancer. This study estimated the influence of anatomic location-based node stations on survival and proposed a new staging method based on both the number and anatomical distribution of metastatic LNs (mLNs). Methods Stage I–III gastric cancer patients with radical gastrectomy were retrospectively evaluated. Overall survival (OS) was estimated in 1786 patients with UICC/AJCC stage N1–N3b disease and compared with estimates obtained using JGCA group 1–3 mLN staging. Results The OS of UICC/AJCC stage N1–N3b patients with group 2 JGCA mLNs was significantly worse than that of patients with only group 1 mLNs. The OS of the patients with group 2 mLNs was similar to that of patients with group 1 mLNs but in the next more advanced UICC/AJCC-N stage. The OS of patients with group 3 mLNs was worse than that of patients with any UICC/AJCC-N stage and was similar to that of N3b patients with group 2 mLNs. A new pathological node (pN) staging classification was developed that advanced the N-staging of patients with group 2 mLNs. It was a better indicator of prognosis than the eighth UICC/AJCC-N and the thirteenth JGCA group staging systems. Conclusions A simple, accurate pN staging system including both the number and location of mLNs had improved homogeneity, discriminatory ability, and gradient monotonicity.