Validation of the Prognostic Value of New Sub-stages Within the AJCC 8th Edition of Non-small Cell Lung Cancer

Background: The 8th edition of the American Joint Committee on Cancer (AJCC) staging system for non-small cell lung cancer (NSCLC) has been released. The current study tried to validate the prognostic significance of the new system among patients registered within the surveillance, epidemiology and end results (SEER) database.

Methods: SEER database (2010-2013) has been accessed through SEER*Stat program and AJCC 8th edition stages were reconstructed utilizing the collaborative stage descriptions. Overall and lung cancer-specific survival analyses according to both 7th and 8th editions were conducted through Kaplan-Meier analysis and multivariate analysis was conducted through a Cox proportional hazard model.

Results: A total of 127,096 patients with NSCLC were identified in the period from 2010 to 2013. For overall survival assessment according to the 8th edition, P values for all pair-wise comparisons among different stages were significant (<0.0001) except for the comparisons between stage IB and IIA (P = 0.146); stage IIA and IIB (P = 0.165). For lung cancer-specific survival according to the 8th edition, P values for all pair-wise comparisons among different stages were significant (<0.001). Among patients with stage I disease, multivariate analysis for factors affecting overall and lung cancer-specific survival among patients with stage I disease was conducted. The following factors were associated with worse overall and lung cancer-specific survival: age ≥70 years, more advanced stage, male gender, squamous histology, no surgery and no radiotherapy (P < 0.0001 for all factors).

Conclusion: This SEER analysis supports the prognostic significance of the added sub-stages described within AJCC 8th edition stages I and III. Further work is needed to incorporate molecular markers and personalize the future editions of the AJCC staging system.