Long-term survival of patients with stage II and III gastric cancer who underwent gastrectomy with inadequate nodal assessment

BACKGROUND Gastric cancer is an aggressive disease with frequent lymph node (LN) involvement. The NCCN recommends a D2 lymphadenectomy and the harvesting of at least 16 LNs. This threshold has been the subject of great debate, not only for the extent of surgery but also for more appropriate staging. The reclassification of stage IIB through IIIC based on N3b nodal staging in the eighth edition of the American Joint Committee on Cancer (AJCC) staging system highlights the efforts to more accurately discriminate survival expectancy based on nodal number. Furthermore, studies have suggested that pathologic assessment of 30 or more LNs improve prognostic accuracy and is required for proper staging of gastric cancer. AIM To evaluate the long-term survival of advanced gastric cancer patients who deviated from expected survival curves because of inadequate nodal evaluation. METHODS Eligible patients were identified from the Surveillance, Epidemiology, and End Results database. Those with stage II-III gastric cancer were considered for inclusion. Three groups were compared based on the number of analyzed LNs. They were inadequate LN assessment (ILA, < 16 LNs), adequate LN assessment (ALA, 16-29 LNs), and optimal LN assessment (OLA, >= 30 LNs). The main outcomes were overall survival (OS) and cancer-specific survival. Data were analyzed by the Kaplan-Meier product-limit method, log-rank test, hazard risk, and Cox proportional univariate and multivariate models. Propensity score matching (PSM) was used to compare the ALA and OLA groups. RESULTS The analysis included 11607 patients. Most had advanced T stages (T3 = 48%; T4 = 42%). The pathological AJCC stage distribution was HA = 22%, IIB = 18%, IIIA = 26%, IIIB = 22%, and IIIC = 12%. The overall sample divided by the study objective included ILA (50%), ALA (35%), and OLA (15%). Median OS was 24 mo for the ILA group, 29 mo for the ALA group, and 34 mo for the OLA group (P < 0.001). Univariate analysis showed that the ALA and OLA groups had better OS than the ILA group [ALA hazard ratio (HR) = 0.84, 95% confidence interval (CI): 0.79-0.88, P < 0.001 and OLA HR = 0.73, 95%CI: 0.68-0.79, P < 0.001]. The OS outcome was confirmed by multivariate analysis (ALA HR = 0.68, 95% CI: 0.64-0.71, P < 0.001 and OLA: HR = 0.48, 95%CI: 0.44-0.52, P < 0.001). A 1:1 PSM analysis in 3428 patients found that the OLA group had better survival than the ALA group (OS: OLA median = 34 mo vs ALA median = 26 mo, P < 0.001, which was confirmed by univariate analysis (HR = 0.81, 95%CI: 0.75-0.89, P < 0.001) and multivariate analysis: (HR = 0.71, 95%CI: 0.65-0.78, P < 0.001). CONCLUSION Proper nodal staging is a critical issue in gastric cancer. Assessment of an inadequate number of LNs places patients at high risk of adverse long-term survival outcomes.