External Validation of AJCC Eighth Edition of Non–small-cell Lung Cancer Staging Among African Americans

Abstract

IntroductionThe American Joint Committee on Cancer (AJCC) eighth staging classification system for non–small-cell lung cancer was based on data from a multinational study consisting of 94,708 patients. African Americans were not included in this large database. Materials and MethodsThe authors aimed to compare the performance of the AJCC eighth staging system with that of the seventh in predicting overall survival among African Americans utilizing the National Cancer Database. Cases with T- and M- categories were classified into 2 groups based on the AJCC seventh and eighth edition staging systems. Kaplan-Meier curves for overall survival were then constructed for each subgroup. Concordance index was computed using Uno’s methodology to assess the overall performance between the 2 staging systems in predicting the mortality. Time-dependent area under the curve was calculated at each follow-up event for the seventh and eighth edition clinical and pathologic staging using an inverse probability of censoring weighted methodology. A 2-sided P-value < .05 was considered to show statistical significance. ResultsThe database identified a total of 70,606 African American patients in the study period of 2004 through 2014. Area under the curve values were consistently higher for the eighth edition scheme compared with the seventh edition (concordance 0.630 vs. 0.624, respectively; P < .0001 for clinical staging scheme and 0.596 vs. 0.591, respectively; P = .01 for pathologic staging scheme). ConclusionThe AJCC eighth edition staging system showed better prognostic value in predicting overall survival when compared with the AJCC seventh edition staging scheme among African American patients with non–small-cell lung cancer.