S. Paul1, S. C. Wang1, M. R. Porembka1 1University Of Texas Southwestern Medical Center,Dallas, TX, USA
Introduction: Gastric cancer is a heterogeneous disease with variable presentation and outcome based on histologic subtype and race. A recent revision to the American Joint Committee on Cancer (AJCC) staging classification for gastric cancer introduced increased subclassification based on the degree of nodal involvement. The impact of race on the prognostic ability of the various staging systems has not been assessed.
Methods: Using the National Cancer Database, we selected patients with gastric adenocarcinoma who underwent upfront surgery between 2006 and 2013 and extracted clinicopathologic data. Stage was assigned in accordance with the 7th and 8th editions of the AJCC pTNM staging systems. Race was classified into Non-Hispanic Whites (NHW), Hispanic (HS), African American (AA) and Asian (AS). Overall survival was estimated using the Kaplan–Meier method and compared using log-rank tests. Multivariable Cox regression was used to estimate factors associated with survival and chi-square analysis was performed to determine effect of race on staging.
Results: We identified 15641 patients. Median age was 67 years (IQR: 57-76) and 60% were male. There were 8970 NHW (57%), 1987 HS (13%), 3153 AA (20%), and 1531 AS (10%) patients. AS patients had significantly more lymph nodes examined (median lymph nodes: AS 17, WNH 14, HS 15, AA 14; p<0.05). The 7th edition system discriminated well between stages, but was not prognostic for Hispanic patients with Stage 3 disease (log-rank p=0.16). Migration between stages was similar between races (2B +1.5%, 3A +4.4%, 3B -3.2%, 3C -2.2%; p>0.05). Discrimination was improved among all races and stages, including Hispanic patients with Stage 3 disease (p<0.001). Adequate lymph node harvest improved the accuracy of both staging systems; however, only the 8th edition was able to discern HS patients with Stage 3 disease.
Conclusion: In a retrospective study of patients undergoing upfront resection for gastric cancer, classification of patients under the 8th edition AJCC staging resulted in better discernment and separation of staging groups among racial groups.