Should patients with stage IB non-small cell lung cancer receive adjuvant chemotherapy? A comparison of survival between the 8th and 7th editions of the AJCC TNM staging system for stage IB patients

IntroductionThe aims of this study were to compare the efficacy of platinum-based adjuvant chemotherapy in resected patients with stage IB NSCLC according to the 7th and 8th editions of the American Joint Committee on Cancer (AJCC) staging manuals on tumor, node, and metastasis (TNM) staging systems, respectively.MethodsThis retrospective analysis included 569 patients who underwent pulmonary resection for primary non-small cell lung cancer. 5-year overall survival (OS) was compared in stage IB disease using the 8th and 7th editions of the TNM classification, respectively. Survival curves were plotted using the Kaplan-Meier method, and log-rank test was used to evaluate differences between subgroups.ResultsThe 5-year overall survival was 76.9% and 83.5% (p=0.044) for patients in the observation and adjuvant groups, respectively. The presence of adjuvant chemotherapy, lymphovascular invasion, TNM stage, and performance status (PS) were risk factors for OS in univariate analysis. In multivariate analysis, TNM stage [hazard ratio (HR) 5.403, 95% confidence interval (CI) 3.743-7.801, p<0.001], PS (HR 4.375, 95% CI 2.856-6.703, p<0.001) and adjuvant chemotherapy (HR 1.476, 95% CI 1.028-2.119, p=0.035) were risk factors for OS. Subgroup analysis showed that for patients with 8th edition stage IB NSCLC, 5-year OS was 87.6% in the observation group (n=265) and 82.4% in the adjuvant group (p=0.021). For patients with 8th edition stage IIA NSCLC, 5-year OS was 48.1% and 87.7% in the observation group and the adjuvant group (p<0.001), respectively. For patients with an Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of 0, a better 5-year OS was seen in the adjuvant group (79.3% vs 91.6%, p=0.001) By contrast, for patients with a PS score of ECOG 1, the 5-year OS was significantly improved in the observation group (58.6% vs 17.2%, p=0.021).ConclusionThe 8th edition of the AJCC staging identified the beneficiary population of platinum-based adjuvant chemotherapy in early-stage NSCLC. Moreover, patients with good PS (ECOG 0) benefited from adjuvant chemotherapy. A large prospective randomized clinical trial is needed to determine the real role of adjuvant chemotherapy in this setting.