The lymph node ratio as a prognostic factor for gastric cancer

To predict prognosis of gastric cancer, an adequate assessment of the stage of gastric cancer is important. The UICC/AJCC TNM classification is the most commonly used classification system. For adequate N staging at least 15 lymph nodes should be retrieved. In some countries, this amount of lymph nodes is not met, which can lead to understaging. Therefore, the lymph node ratio (LNR) is proposed as an alternative N staging modality. The purpose of this study was to compare the different staging modalities. Patients and methods. We included all patients who underwent surgery for gastric cancer, newly diagnosed between 2000 and 2009 and staged patient by UICC/AJCC TNM 5th/6th or 7th and by LNR. We conducted crude survival analysis, univariate and multivariate analyses according to the different staging systems. Results. The five-year overall survival rates ranged from 58% for N0 disease to 18% in case of more than 15 metastatic lymph nodes. The distribution of overall five-year survival according to LNR was 58% for LNR0 and 10% for LNR3. Univariate analysis showed that all the UICC/AJCC TNM classification systems as well as the LNR were strong prognostic factors for overall survival. The LNR correlated less with the number of nodes examined. Conclusion. LNR is a good prognostic tool for overall survival, it is an independent prognostic factor with a more homogenous spread of hazard ratios and five-year survival rates than UICC/AJCC systems. Furthermore, the LNR has a lower correlation with the number of nodes examined, making it less vulnerable for stage migration.