Validation of the 8th AJCC staging system for gastric cancer in a population-based setting.

BACKGROUND

The aim of this analysis is to validate the prognostic value of the 8 edition of the American Joint Committee on Cancer (AJCC) staging system for gastric cancer.

METHODS

Through SEER*Stat program, Surveillance, epidemiology and end results database (2010-2013) was accessed and 8th AJCC stages were reconstructed. Cancer-specific survival analyses according to both 7th and 8th editions were conducted through Kaplan-Meier analysis/log-rank testing and multivariate analysis was conducted through a Cox model.

RESULTS

Among pathologically-staged patients, P values for pairwise comparisons among different 8th AJCC stages were significant (<0.05) for all comparisons except for stage IIIC vs. IV; while P values for pairwise comparisons among different 7th AJCC stages were significant (<0.05) for all comparisons except for stage IIIA vs. IIIB and stage IIIC vs. IV. Among clinically-staged patients and according to either the clinical 8th AJCC or the 7th AJCC, significant overlap in outcomes existed between different stages. Among pathologically-staged patients, c-statistic for the pathological 8th system was: 0.762; while for the 7th system, it was: 0.763. Among clinically-staged patients, c-statistic for the clinical 8th system was: 0.634; while for the 7th system, it was: 0.637.

CONCLUSION

Compared to the 7th system, the 8th system does not bring about significant prognostic improvement (for either clinically- or pathologically-staged patients).