Risk factors for tumor recurrence in patients with early-stage (stage I and II) non-small cell lung cancer: Patient selection criteria for adjuvant chemotherapy according to the seventh edition TNM classification

Objectives: The purpose of this study was to evaluate risk factors for tumor recurrence in patients with completely resected early-stage non-small cell lung cancer (NSCLC). Methods: Between July 1992 and December 2007, 1,967 consecutive patients with stage I and II NSCLC with diagnoses based on the seventh edition TNM classification underwent complete resection. All patients were divided into three groups according to the stage and presence of lymph node metastasis:stage I, patients with stage I, T1-T2aN0M0 disease; stage IIN0, patients with stage II, T2b-T3N0M0, node-negative disease; and stage IIN1, patients with stage II, T1-2N1M0, node-positive disease. Freedom from recurrence rate was estimated using the Kaplan-Meier method, and recurrence risk factors were identified by univariate and multivariate analyses. Results: The 5-year freedom from recurrence rates for stage I, stage IIN0, and stage IIN1 patients were 84%, 61%, and 54%, respectively. By multivariate analyses, three variables (histologic differentiation, vessel invasion, and visceral pleural invasion) in stage I and two variables (adenocarcinoma histology and visceral pleural invasion) in stage IIN0 and stage IIN1 were shown to be independently significant risk factors for recurrence. According to subgroup analyses that combined these risk factors in each group, the 5-year freedom from recurrence rate was 63% for stage I with three risk factors, whereas those for stage IIN0 and stage IIN1 without risk factors were 83% and 78%, respectively. Conclusion: In patients with stage I and II NSCLC, we identified risk factors for recurrence. When these factors are combined, high- and low-risk subgroups can be identified within each group.