Background: Small cell lung cancer (SCLC) is usually classified using the limited and extensive definition. The tumor, node, metastasis (TNM) classification should also be applicable to SCLC, but it has only been reported in small surgical series. The current analysis looks to the impact of the TNM system on the clinical staging of SCLC and of the new International Association for the study of Lung Cancer (IASLC) proposals.
Methods: Using the IASLC database, survival analyses were performed for clinically staged patients. 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.
Results: The IASLC database contained 12,620 eligible cases of small cell histology. TNM staging was available for 8088 patients. Survival was directly correlated to both T and N category. Differences were more pronounced in patients without mediastinal or supraclavicular nodal involvement. Stage grouping using the sixth edition of TNM also differentiates survival except between IA and IB. Patients with pleural effusion regardless of the cytology have an intermediate prognosis between limited and extensive disease. The IASLC proposals for the seventh edition of the TNM classification also apply to this series of SCLC and to the SEER database.
Conclusion: TNM staging is recommended for SCLC, and stratification by stage I-III should be incorporated in clinical trials of early-stage disease. Further studies are needed to clarify the impact of pleural effusion and the extent of N3 disease.