Positive lymph node ratio as a novel indicator of prognosis in gastric signet ring cell carcinoma: a population-based retrospective study

Background: Lymph node status has a strong predictive effect on the prognosis of all patients with gastric cancer. It is unclear whether the positive lymph node ratio (PLNR) is a reliable prognostic factor for gastric signet ring cell carcinoma (SRCC). Methods: Patients with SRCC were obtained from the Surveillance, Epidemiology and End Results (SEER) database for the years 1998-2013. Cutoff values of positive lymph node ratio (PLNR) were decided using X-tile program. Survival was determined using the Kaplan-Meier method. Univariate and multivariate analyses were used to identify prognosticator of gastric signet ring cell carcinoma. Results: A total of 1,884 cases were identified. 0.8 as the optimal cutoff value to separate the patients into high and low risk subsets in accordance of cancer-caused survival in SRCC patients (the number as 0.8, P<0.0001). Patients with PLNR>0.8 remained to have a poorer prognosis compared with those with PLNR<0.8 as shown by both OS (HR=2.083, 95% CI: 1.862-2.33, P<0.001) and CSS (HR=2.052, 95% CI: 1.802-2.336, P=0.014) in the multivariate cox regression model. Conclusions: PLNR is of great significance in the evaluation of prognosis for patients with SRCC.