The IASLC Lung Cancer Staging Project: Proposals Regarding the Relevance of TNM in the Pathologic Staging of Small Cell Lung Cancer in the Forthcoming (Seventh) Edition of the TNM Classification for Lung Cancer

IntroductionFor more than 50 years, small cell lung cancer (SCLC) has been staged mainly as either limited or extensive stage disease. Small published series of resected SCLC have suggested that the tumor, node, metastases (TNM) pathologic staging correlates with the survival of resected patients. Recent analysis of the 8088 cases of SCLC in the International Association for the Study of Lung Cancer (IASLC) database demonstrated the usefulness of clinical TNM staging in this malignancy. The IASLC data bank contains an unprecedented number of resected SCLC cases with pathologic staging information. This analysis was undertaken to examine the impact of the TNM system on the pathologic staging of SCLC and to assess the new IASLC proposals in this subtype of lung cancer.MethodsUsing the IASLC database, survival analyses were performed for resected patients with SCLC. Prognostic groups were compared, and the new IASLC TNM proposals were applied to this population and to the Surveillance, Epidemiology, and End Results (SEER) database.ResultsThe IASLC database contained 349 cases of resected SCLC where pathologic TNM staging was available. Survival after resection correlated with both T and N category with nodal status having a stronger influence on survival. Stage groupings using the 6th edition of TNM clearly identify patient subgroups with different prognoses. The IASLC proposals for the 7th edition of TNM classification also apply to this population and to the SEER database.ConclusionThis analysis further strengthens our previous recommendation to use TNM staging for all SCLC cases.