External Validation of a Nomogram Developed for Predicting Overall Survival in Gastric Cancer Patients with Insufficient Number of Examined Lymph Nodes.

Objectives: Nomograms and scoring systems in gastric cancers have been mainly developed based on adequate lymph node (IN) dissections. This study aimed to perform external validation of a nomogram developed for predicting overall survival (OS) in gastric cancer patients with insufficient number of examined LNs (eLNs) and to evaluate its usability as compared with the 8th American Joint Committee on Cancer (AJCC)'s Tumor-Node-Metastasis staging system. Methods: Medical records of 262 patients undergoing complete surgical resection for gastric cancers and having pathologically confirmed diagnosis were retrospectively reviewed. The study included 104 (39.7%) patients (82 males, median age, 60.3 years) with insufficient number of eLNs (<16). The 5-year OS rate was calculated using the nomogram and according to the AJCC system. Results:The median follow-up period was 37.4 months (range: 0.9-122.9). Of the patients, 69 (66.3%) died and 35(33.7%) achieved 5-year survival within the follow-up period. The nomogram and the AJCC system predicted OS were significantly lower in patients who died than in those who achieved 5-year survival (p<0.001 for both). According to the receiver operative characteristics-curve, the area under the curve for the nomogram (0.801; 95% CI, 0.715-0.887; p<0.001) was larger than that for the AJCC system (0.754; 95% CI, 0.659-0.849; p<0.001). Conclusion: The nomogram developed for gastric cancer patients with insufficient number of eLNs (<16) was effective in predicting 5-year OS in our cohort and was superior to the AJCC system.