Neoadjuvant chemoradiotherapy versus neoadjuvant chemotherapy for patients with stage III-N2M0 non-small cell lung cancer (NSCLC): A population-based study.

Abstract

8503 Background: Stage III-N2 non-small cell lung cancer (NSCLC) is a heterogeneous disease with controversial management options. Induction therapy as part of multimodal treatment is the standard of care for Stage III-N2 NSCLC. We aim to investigate the effect of adding radiotherapy to neoadjuvant chemotherapy on survival outcomes. Methods: All adult NSCLC patients diagnosed between 2004 and 2015 were identified in the Surveillance, Epidemiology, and End Results (SEER) database using ICD-O-3 histologic type coding. Inclusion criteria involved stage III NSCLC patients with ipsilateral lymph node involvement (N2), of any T stage, and with no known distant metastasis (M0). Our main sub-cohorts were patients who either underwent chemoradiotherapy (CRT) or chemotherapy (CT) in neoadjuvant settings. Our primary outcomes were overall survival (OS) and cancer-specific survival (CSS) in months. Cox proportional hazards model was used to analyze the effect of each treatment modality on OS and CSS in univariate and multivariate fashions. Multivariate analysis was adjusted for age, sex, marital status, T stage, resected lymph node status, tumor histology, primary site, laterality, and surgical procedure. Inverse probability treatment weighting (IPTW) was applied to create weighted samples based on study covariates. Results: Our analysis included 1175 patients; 799 (68.0%) underwent neoadjuvant CRT and 376 (32.0%) underwent neoadjuvant CT. Sample median age was 63 (IQR:56-69) years. T2 stage was the most prevalent (N =561, 47.7%), followed by T4 (N=243, 20.7%), T1 (N=228, 19.4%), and T3 (N=143, 12.2%). The main tumor histology was non-squamous cell carcinoma in 773 (65.8%) patients. The upper lobe was the most common primary tumor site (N =788, 67.1%). Patients underwent lobectomy (N=917, 78.0%), pneumonectomy (N=184, 15.7%), or sub-lobar resection (N=69, 5.9%). Adding radiotherapy to chemotherapy showed a slightly higher median OS than chemotherapy alone in neoadjuvant settings (51 vs. 47 months, respectively), and a higher median CSS (75 vs. 59 months, respectively). However, these differences were not statistically significant for OS or CSS (HR = 1.08, 95% CI: 0.91-1.28 and HR = 1.04, 95% CI: 0.89-1.21, respectively). After adjustment, age, T3-T4 stage, non-squamous histology, lower lobe primary site, positive resected lymph nodes, and pneumonectomy were all significant independent predictors for worse OS and CSS. IPTW analysis showed no remarkable survival advantage for CRT patients (HR = 1.15, 95% CI: 0.95-1.40 and HR= 1.12, 95% CI: 0.90-1.39) for OS and CSS, respectively. Conclusions: Adding radiotherapy to neoadjuvant CT did not result in significant survival benefits. Multiple prognostic factors should be taken into consideration when identifying the optimal choice and sequence of multimodal treatment for stage III-N2M0 NSCLC patients.