Comparative survival after neoadjuvant vs adjuvant systemic therapy in resectable stage II and stage III non-small cell lung cancer: A retrospective study using the National Cancer Database.

8075 Background: Resectable Stage II and III Non-small Cell Lung Cancer (NSCLC) are managed with surgery and perioperative systemic therapy Chemo/Chemo-Immunotherapy (IO). However, there lacks a consensus in optimal selection between neoadjuvant and adjuvant approaches. Hence, it underscores the necessity to undertake a comparative survival outcome associated with systemic therapy in these distinct settings. Methods: We conducted an analysis, of individuals aged 18 and above diagnosed with stage II and stage III NSCLC between 2004 - 2020, using data from the National Cancer Database (NCDB). Overall survival (OS) was compared for both Neoadjuvant and Adjuvant systemic therapy using Cox proportional hazards models after adjusting for sociodemographic (e.g., age, sex, race-ethnicity, and income) and health (e.g., insurance and facility type) related factors. The inclusion criteria involved restricting the analysis to individuals with no more than one lifetime cancer diagnosis and excluding those who received radiation therapy. Results: Among approximately 2 million total patients with NSCLC in NCDB, 8.38% and 20% were stage II and III respectively. After we identified a total of 137,473 eligible patients, 27,115 had relevant treatment information with 2,550 Neoadjuvant Chemo, 112 Neoadjuvant chemoIO, 24,175 Adjuvant chemo and 278 Adjuvant chemoIO. A statistically significant association between OS and treatment group was observed χ2(3) =55.5, p<.001. The OS was notably higher in the Neoadjuvant chemoIO group (78.57%) compared to Adjuvant chemoIO group (55.76%), whereas the Neoadjuvant chemo-only group exhibited lower OS (45.41%) compared to the Adjuvant chemo group (47.98%). The Cox proportional hazards model showed 70% higher mortality risk in the Adjuvant chemoIO group compared to the Neoadjuvant chemoIO group (p=0.030, 95% CI 1.05-2.77). The 2-year and 5-year OS rates for Neoadjuvant ChemoIO were 77.9% and 68.8%, respectively versus 68.7% and 42.8% for Adjuvant chemoIO group. Conclusions: Our analysis reveals that Neoadjuvant chemoIO demonstrates superior survival outcomes compared to Adjuvant chemoIO. Additionally, our findings suggest the potential predictive value of Immunotherapy in combination with chemotherapy in the Neoadjuvant setting. Key Words: NSCLC, Neoadjuvant treatment, Adjuvant treatment, Chemotherapy, Immunotherapy, OS.