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

Purpose: To propose changes in the seventh revision of the tumor, node, metastasis (TNM) classification for lung cancer.

Methods: Data 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.

Results: On the basis of the optimal cutpoints, pT1NOR0 was divided into pT1a < or =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%.

Conclusion: Recommended 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.