Impact of adjuvant chemotherapy on patients with stage IB non-small cell lung cancer with visceral pleural invasion.

Background:Adjuvant chemotherapy has reduced the risk of recurrence and death in stage IB non-small cell lung cancer (NSCLC) with high-risk factors; however, the impact of visceral pleural invasion (VPI) on outcomes in stage IB NSCLC treated with adjuvant chemotherapy remains controversial. The aim of this study was to explore the clinical and prognostic significance of adjuvant chemotherapy for stage IB (1-4 cm) NSCLC with VPI. Methods:This retrospective study included 251 patients admitted between January 2008 and May 2018 from four hospitals who underwent complete resection for Tumor-Node-Metastasis (TNM) 8th edition stage IB NSCLC with VPI. The relationship between adjuvant chemotherapy and overall survival (OS) or recurrence-free survival (RFS) was analyzed using the Kaplan-Meier method and Cox proportional hazards model. Results:Of 251 patients with stage IB NSCLC with VPI, 122 (48.6%) received adjuvant chemotherapy after surgical resection and 129 (51.4%) were placed under observation. Multivariable analysis showed that adjuvant chemotherapy was an independent predictor of RFS [adjusted hazard ratio (aHR), 0.57; 95% confidence interval (CI): 0.33-0.96; P=0.036]. A micropapillary pattern (aHR, 2.46; 95% CI: 1.33-4.55; P=0.004) and lymphovascular invasion (aHR, 2.86; 95% CI: 1.49-5.48; P=0.002) were associated with a higher risk of recurrence. Multivariable analysis also showed that adjuvant chemotherapy was an independent predictor of OS (aHR, 0.22; 95% CI: 0.09-0.58; P=0.002). In a subgroup analysis of patients with a tumor size of 1-3 cm, adjuvant chemotherapy was associated with improved RFS and OS, and this association was maintained even when patients with VPI had additional risk factors. Conclusions:Our study shows that adjuvant chemotherapy is appropriate for patients with stage IB (1-4 cm) NSCLC with VPI, and even those with smaller tumors (1-3 cm).