Validation study of the proposed IASLC staging revisions of the T4 and M non-small cell lung cancer descriptors using data from 23,583 patients in the California Cancer Registry

Background: We performed a validation study of the proposed International Association for the Study of Lung Cancer (IASLC) tumor, node, metastasis (TNM) and stage grouping revisions on advanced nonbronchioloalveolar carcinoma (non-BAC) non-small cell lung cancer (NSCLC). Methods: Twenty-three thousand five hundred eighty-three patients from the California Cancer Registry between 1999 and 2003 with histologically confirmed non-BAC NSCLC and complete TNM staging were identified and reclassified according to the IASLC proposed TNM revisions and new stage groupings. Twelve thousand nine hundred one stage IIIB and IV patients formed the primary analysis of the changes to T4 and M descriptors. Surveillance, Epidemiology, and End Results extent of disease codes were used to identify various T4 and M descriptors. Cox proportional hazards regression was used to calculate hazard ratios (HRs) among the stage groupings of the current and proposed staging system with adjustment for ethnicity, gender, age, histology, histologic grade, socioeconomic status, surgery, radiation, and chemotherapy. Results: The proposed changes to the T4 and M descriptors were supported by overall survival analysis. T4 due to additional nodules had significant survival advantage over other T4 and M descriptors among non-BAC NSCLC and individual histology and warrants down-staging to T3. Pericardial effusion had survival similar to M1b patients. Cox proportional hazards regression analysis supports subdividing M descriptor into M1a (versus IASLC stage IA; HR = 4.90; 95% confidence interval: 4.49-5.34) and M1b (versus IASLC stage TA; HR = 6.84; 95% confidence interval: 6.30-7.44). Conclusions: IASLC has greatly improved the T4 and M descriptors allowing better prognostication of advanced non-BAC NSCLC. Pericardial effusion may be considered as M1b rather than M1a.