The Role of Adjuvant Chemotherapy in Patients With Stage IB Non-Small Cell Lung Cancer

Abstract

The 8th AJCC TNM staging system has re-defined stage IB NSCLC as tumor size of 3-4cm (including 4cm) and negative lymph node. The efficacy of adjuvant chemotherapy after surgical resection still remains controversial, and adjuvant chemotherapy is not recommended as regular treatment for stage IB NSCLC. Here we aimed to access the efficacy of adjuvant chemotherapy after surgical resection in stage IB NSCLC patients, and identify the potential high-risk factors associated with the efficacy of adjuvant chemotherapy.Resected NSCLC patients with 3cm < tumor size≤4cm and negative lymph node diagnosed from 2009 to 2015 were retrieved from the SEER database (Surveillance, Epidemiology, and End Results Program). Age, gender, tumor size, histologic type, differentiation, pleural invasion, adjuvant chemotherapy or not, and surgery type of patients were collected. The Kaplan-Meier and log rank test were used to perform univariate survival analysis. Cox proportional hazards regression models was used to evaluate the association of high-risk features with survival. STATA software was used for data sorting and statistical analyses.A total of 3236 operable IB NSCLC were enrolled in this study, in which 395(12.21%) patients received adjuvant chemotherapy and 2841 (87.79%) not. Univariate and multivariate analyses showed that, age > 70 (HR, 1.88; P < 0.0001), male (HR, 1.32; P = 0.004), poor differentiation (HR = 1.35; P = 0.002) and wedge resection (HR, 1.68; P < 0.0001) were independent risk factors for overall survival (OS) of IB NSCLC patient. Notably, adjuvant chemotherapy did not affect the overall survival (OS) of patients with IB NSCLC (HR, 0.86; 95% CI, 0.70 to 1.08; P = 0.20), and the 5-year OS were 61.31% and 65.54% in observation group and adjuvant group, respectively. To further identify the patients with high-risk factors who might benefit from adjuvant chemotherapy, subgroup analysis was performed and the results indicated tumor size equal to 4 cm was the only high-risk factors associated with the efficacy of adjuvant chemotherapy (HR, 0.46; 95% CI, 0.29 to 0.73; P = 0.01).Age, gender, tumor differentiation, and wedge resection were independent factors for resected IB NSCLC patients. IB NSCLC patients with 4 cm tumor were recommended to perform adjuvant chemotherapy after surgical resection, and other patients were recommended to enter observation phrase.