Background: The presence of metastatic lymph nodes is the most important prognostic factor for gastric carcinoma; however, the optimal system for the accurate staging of lymph node metastasis for patients with gastric cancer remains controversial. This study was designed to compare five systems in relation to the N classification of gastric carcinoma.
Materials and methods: This multicentric historical cohort study was conducted on 148 patients with M0 gastric adenocarcinoma who underwent gastrectomy in, five referral hospitals in Iran. Lymph nodes were sectioned, stained with hematoxyl in and eosin. The lymph node status was classified according to the five systems which are: The number of involved lymph nodes (TNM staging), metastatic lymph node ratio (N ratio), and the largest involved lymph node size, largest metastatic nest size and largest metastatic nest to lymph node size ratio.
Results: Patients were classified into significant prognostic groups by the five N classification method including the TNM method, N ratio (0, ≤0.15, 0.15-0.4, >0.4), largest involved lymph node size (0, ≤5, 5-11, >11 mm), Largest metastatic nest size (≤1, 1-7.5, >7.5 mm) and largest metastatic nest to lymph node size ratio (≤0.3, 0.3-0.9, >0.9). All of the above systems remained as independently significant prognostic factors in terms of overall and disease free survival time.
Conclusion: Among the N staging systems we recommend the metastatic lymph node ratio and largest metastatic nest to lymph node size systems, since they are reproducible, simple, have good survival applicability, have prognostic value and include less stage migration especially in patients whom fewer than 15 lymph nodes are dissected.
Keywords: Gastric carcinoma; TNM system; lymph node metastasis; metastatic nest; staging.