Ratio between metastatic and examined lymph nodes (N ratio) may have low clinical utility in gastric cancer patients treated by limited lymphadenectomy: results from a single-center experience of 526 patients

BACKGROUND: The aim of this study was to evaluate the prognostic value of the ratio of metastatic to examined lymph nodes (N ratio) in gastric cancer patients who underwent limited lymphadenectomy and had a small number (< or =15) of analyzed nodes. METHODS: The prognostic value of the actual AJCC/UICC pN staging system and the N ratio (0%, 1-25%, > 25%) were analyzed by means of univariate and multivariate analyses for 526 patients who underwent R0 resection for gastric adenocarcinoma at the Latvia Oncology Center. RESULTS: The mean (SD) number of analyzed nodes was 5.6 (2.8). The number of positive nodes significantly increased with the number of analyzed nodes (p < 0.001). No significant differences in survival (p = 0.508) and risk of death (p = 0.224) were observed between pN1 and pN2 subsets. When the N ratio (1-25% vs. > 25%) was taken into account, a significant difference was demonstrated between pNR1 and pNR2 with respect to survival (p = 0.017) and risk of death (p = 0.012). Nonetheless, the joint allocation of the two classifications demonstrated that only a minority of patients (28 cases) belonged to the pNR1 subset and none of these belonged to the AJCC/UICC pN2 subset. CONCLUSIONS: When a small number of lymph nodes are analyzed, the N ratio can discriminate patients better than TNM classification. However, because a small number of retrieved nodes produced only a small number of pNR1 patients, the N ratio classification cannot be justified for clinical use.