Propensity score-matched analysis of adjuvant chemotherapy for stage I non-small cell lung cancer

Objective: The aim of this study was to reevaluate the role of adjuvant chemotherapy for patients with stage I non-small cell lung cancer (NSCLC). Methods: Data from 800 patients with completely resected pathologic stage I NSCLC who received adjuvant chemotherapy (n = 191) and those who did not (n = 609) were analyzed retrospectively and propensity score-matched pairs were determined. Results: Although recurrence-free survival (RFS) and overall survival (OS) were not significantly different between patients who received adjuvant chemotherapy and those who did not in the univariate analyses, multivariate Cox analyses demonstrated that adjuvant chemotherapy was an independent prognostic factor for RFS and OS (P = .008 and P = .009, respectively). In 159 propensity score-matched pairs, including variables such as age, gender, smoking history, comorbidity, postoperative complication, histology, size of the invasive component of the tumor, and status of lymphatic, vascular, and pleural invasion, RFS and OS were considerably better in patients who received adjuvant chemotherapy (5-year RFS rate, 79.8%; 5-year OS rate, 89.3%) than in those who did not (5-year RFS rate, 60.2%; 5-year OS rate, 75.2%). Patients who received adjuvant chemotherapy showed significantly better RFS than those who did not in the group with an invasive component larger than 2 cm (5-year RFS rate, 74.4% vs 55.2%; P = .015) or in those with positive lymphatic invasion (5-year RFS rate, 63.3% vs 44.8%; P = .05). Conclusions: Adjuvant chemotherapy is effective for patients with stage I NSCLC, particularly those with an invasive component larger than 2 cm or those with lymphatic invasion.