Prognosis for gastric carcinomas with an insufficient number of examined negative lymph nodes.

Abstract Background The optimal system for lymph node (LN) staging in gastric cancer is still a subject of debate. The aim of our study was to analyse the probability of error in negative LN (pN0) gastric carcinomas when a low number of LNs were harvested using a probabilistic model. Methods Patients with gastric carcinoma who underwent R0 resection at three university hospitals between 2004 and 2009 were retrospectively included. A Bayesian model was used to analyse the probability of error for negative LNs (pN0) gastric carcinomas. Kaplan–Meier survival curves and the log-rank test were used to compare the overall and specific mortality of prognosis groups. Results Of the 291 patients included, 123 were classified as pN0 (42%). A significant correlation was found between the extent of the LN dissection performed and the number of the LNs retrieved. According to the Bayesian model the carcinomas with 9 or fewer negative lymph nodes were considered to have a high risk (HR) of misclassification, whereas patients with 10–25 LNs analysed and those with more than 26 negative lymph nodes were considered to have a moderate risk (MR) and low risk (LR), respectively. The log-rank test showed a significant improvement in the disease-specific survival for the MR pN0 ( p p Conclusions The proposed probabilistic model is clinically useful for differentiating the prognosis in pN0 gastric carcinomas when an insufficient number of negative lymph nodes are retrieved.