Validation of the Eighth Edition TNM Lung Cancer Staging System

We performed a validation study at our institution, the International Union Against Cancer (Union for International Cancer Control latest version of TNM Classification of Malignant Tumors Eighth Edition).

Data were collected from the Queensland Oncology Online registry of NSCLC or SCLC cases between 2000 and 2015 and validated against the Queensland Integrated Lung Cancer Outcomes Project registry using case identification number, first name, last name, and date of birth. Where data were available, cases were classified according to the Union for International Cancer Control TNM seventh edition stage groupings and then compared with the eighth edition groupings. Kaplan-Meier curves were plotted, and the log-rank test of survival differences was performed with SPSS version 25 (IBM Corp, Armonk, NY).

Of the 3636 cases, 3352 and 1031 had complete clinical and pathologic staging, respectively. Median survival time was found to reduce with increasing clinical stage: seventh edition (IA: 88, IB: 44, IIA: 31, IIB: 18, IIIA: 15, IIIB: 8, and IV: 5 mo) versus eighth edition TNM stage (IA1: not reached, IA2: 88, IA3: 53, IB: 56, IIA: 36, IIB: 22, IIIA: 14, IIIB: 9, IIIC: 8, IVA: 6, and IVB: 3 mo). A similar overall pattern was reflected in the pathologic stage: seventh edition (IA: 124, IB: 110, IIA: 48, IIB: 42, IIIA: 26, IIIB: 31, and IV: 27 mo) versus eighth edition (IA1: not reached, IA2: 122, IA3: 125, IB: 144, IIA: 98, IIB: 57, IIIA: 31, IIIB: 24, and IVA: 7 mo). The log-rank test for survival curves was significant at p < 0.001.

Our external validation study confirms the prognostic accuracy of the eighth edition TNM lung cancer classification. Our analyses also indicated that IIIB, IIIC, and IVA stage groups had similar survival outcomes and suggest further research for refinement.