Applicability of the revised International Association for the Study of Lung Cancer staging system to operable non-small-cell lung cancers

Objective: A new staging system for lung cancer has been proposed by The International Association for the Study of Lung Cancer Staging Committee. We assessed the feasibility of this system for surgical patients. Methods: We reviewed the surgical outcome of 1623 consecutive patients with non-small-cell lung cancer (NSCLC), who underwent pulmonary resection in our institution, with regard to the subpopulations categorised in the current and proposed (2009) systems for postoperative pathologic staging. Results: The proportion of patients staged as IIA, IIB, IIIA and IV increased, while those staged as IB and IIIB decreased. Diseases staged as IIIA or earlier were significantly increased in the new system (current system: N = 1281, 78.9% vs new system: N = 1457, 89.8%). The 5-year survival rates of patients with new stages IB and IIA were clearly dissociated with 72.5% and 51.3%, respectively (P ≪ 0.0001). The 5-year survival rates of the newly classified T1 patients were 90.3% for T1aN0M0 and 81.5% for T1bN0M0 (P = 0.009). Re-classification of T2bN0M0 as stages IIA and T3 (same lobe nodules) N0M0 as stage IIB appropriately emphasised prognostic differences, while T4 (ipsilateral different lobe nodules) N2–3M0 (stage IIIB) and M1a (pleural effusion, stage IV) did not. Conclusions: This study demonstrated that the new system is superior to the current system in terms of the proportion and prognostic prediction of each stage, although it contains minor contradictions. Therefore, revision of the staging system will contribute to the decision for limited operation and adjuvant therapy of resected NSCLC.