Comparison of 7th and 8th editions of the UICC/AJCC TNM staging for non-small cell lung cancer in a non-metastatic North American cohort undergoing primary radiation treatment

Abstract

Background: We compared the performance of 7th and 8th edition of the Union for International Cancer Control (UICC) / American Joint Committee on Cancer (AJCC) TNM staging for non-small cell lung cancer (NSCLC) in non-metastatic (stage I-III) North American cohort undergoing primary radiation treatment.

Methods: Newly diagnosed NSCLC between (Jan 2011 - Dec 2014) were screened through a Canadian Provincial Cancer Registry. Clinico-radiologically and pathologically confirmed non-metastatic NSCLC undergoing primary radiation treatment were included. Kaplan-Meier methods, Cox proportional hazard regression and Akaike information criterion (AIC) were applied to evaluate discriminatory ability and prognostic performance of 7th and 8th edition of staging systems.

Results: In this cohort of 295 patients, 8th edition stages IA3, IB, IIA, IIB, IIIA, IIIB, and IIIC showed progressive increase in the hazard ratio compared to best stage IA2 (8th edition IA3 vs IA2: HR 1.72; IB vs IA2: HR 2.04; IIA vs IA2: HR 2.66; IIB vs IA2: HR 2.91; IIIA vs IA2: HR 3.38; IIIB vs IA2: HR 3.62 and IIIC vs IA2: HR 8.22). In a multivariate model, 8th edition stage grouping had smaller AIC of 2342.08 compared to 7th edition 2349.55, confirming better performance. International Association for the Study of Lung Cancer (IASLC) map based nodal categorization N1, N2 and N3, showed good survival and hazard discrimination over stage N0 (1.39, 1.48 and 2.16 respectively).

Conclusion: In an independent cohort of non-metastatic NSCLC undergoing primary radiation treatment, improved performance of 8^th edition UICC/AJCC staging system over 7th edition was observed.

Keywords: Nonsmall cell lung cancer; Radiation treatment; Staging.