The IASLC Lung Cancer Staging Project: Proposals for the Revision of the T Descriptors in the Forthcoming (Seventh) Edition of the TNM Classification for Lung Cancer

PurposeTo propose changes in the seventh revision of the tumor, node, metastasis (TNM) classification for lung cancer.MethodsData on 100,869 patients were submitted to the international database, and data for 18,198 of these patients fulfilled the inclusion criteria for the T component analysis. Survival was calculated for clinical and pathologic T1, T2, T3, T4NOMO completely resected (R0), and for each T descriptor. A running log-rank test was used to assess cutpoints by tumor size. Results were internally and externally validated.ResultsOn the basis of the optimal cutpoints, pT1NOR0 was divided into pT1a ≤2 cm (n = 1816) and pT1b >2 to 3 cm (n = 1653) with 5-year survival rates of 77 and 71% (p < 0.0001). The pT2NOR0 cutpoints resulted in pT2a >3 to 5 cm (n = 2822), pT2b >5 to 7 cm (n = 825), and pT2c >7 cm (n = 364). Their 5-year survival rates were 58, 49, and 35% (p < 0.0001). For clinically staged N0, 5-year survival was 53% for cT1a, 47% for cT1b, 43% for cT2a, 36% for cT2b, and 26% for cT2c. pT3NO (n = 711) and pT4 (any N) (n = 340) had 5-year survival rates of 38 and 22%. pT4 (additional nodule(s) in the same lobe) (n = 363) had a 5-year survival rate of 28%, similar to pT3 (p = 0.28) and better than other pT4 (p = 0.0029). For pM1 (ipsilateral pulmonary nodules) (n = 180), 5-year survival was 22%, similar to pT4. For cT4-malignant pleural effusion/nodules, 5-year survival was 2%.ConclusionRecommended changes in the T classification are to subclassify T1 into T1a and T1b, and T2 into T2a and T2b; and to reclassify T2c and additional nodule(s) in the same lobe as T3, nodule(s) in the ipsilateral nonprimary lobe as T4, and malignant pleural or pericardial effusions as M1.