At the time the database was closed to additional entries, 100,869 cases had been submitted from 45 sources in 20 countries.7 The final data set involved 81,015 cases after exclusion of ineligible cases (due to incomplete information in 42%, outside the 1990 to 2000 time frame in 28%, unknown histology in 13%, incomplete survival data in 6%, recurrent cases in 6%, and ineligible histologic types in 6% [carcinoid, sarcoma, and others]).5,7 Small cell lung cancer accounted for 16% and NSCLC for 84% of cases. Only the NSCLC cases were used to derive the T, N, M descriptors and stage groupings reviewed in this article. SCLC and carcinoid tumor staging are addressed in separate publications.8,9 The database included cases from four continents (the proportion of NSCLC cases is as follows: Europe, 58%; North America, 21%; Asia, 14%; and Australia, 7%). Submitted cases came from series (40%), registries (30%), and clinical trials (30%). Treatment involved surgery only in 41%, radiotherapy only in 11%, chemotherapy only in 23%, and combined modalities in the rest. Clinical staging included patients subsequently treated with neoadjuvant (preoperative) therapy, whereas preoperatively treated patients were excluded from analyses of pathologic staging.