Validation of the lung cancer staging system revisions using a large prospective clinical trial database (ACOSOG Z0030)

A new revision of the international lung cancer staging system has been recently introduced. The revisions are largely focussed on the T descriptor. We sought to test the validity of this new system on a separate prospectively collected cohort of patients from a recent multicentre trial of early-stage lung cancer. We reviewed the prospectively collected data from 1012 patients undergoing pulmonary resection for early-stage lung cancer in the ACOSOG Z0030 trial. TNM descriptors and overall staging were assessed using both the sixth and seventh editions of the American Joint Committee on Cancer and the Union Internationale Contre le Cancer (AJCC/UICC) lung cancer staging system. Survival results were analysed according to both staging allocations. Using the proposed criteria, the number of patients by stage in the sixth and seventh edition allocations, respectively, were as follows: IA (432, 431); IB (402, 303); IIA (39, 167); IIB (94, 70); IIIA (26, 40); IIIB (19,0); there were no stage IV patients by either version. Overall, 180 (18%) patients had a change in the stage group from the sixth to seventh edition versions with 76 (8%) being downstaged and 104 (10%) being upstaged. In the sixth edition staging system based on pathological stages, median survivals in years were as follows: IA, NA; IB, 7.7; IIA, 4.0; IIB, 3.6; IIIA, 2.6 and IIIB, 2.4. Five-year survivals were: IA, 76.4%; IB, 62.0%; IIA, 47.8%; IIB, 40.4%; IIIA, 31.3% and IIIB, 44.4%. In the new system, median survivals in years were as follows: IA, NA; IB, 8.2; IIA, 4.4; IIB, 3.6 and IIIA, 1.8. Five-year survivals were: IA, 76.9%; IB, 65.0%; IIA, 48.5%; IIB, 42.9% and IIIA, 30.6%. Survival analysis and Kaplan-Meier survival curves showed more monotonic progression, distinction and homogeneity within groups in the seventh edition. This study provides an external validation of the recently revised lung cancer staging system using a large multicentre database. The seventh edition of the AJCC/UICC lung cancer staging system appears to be an improvement over the preceding system.