National guideline concordance and outcomes for pathologic N2 disease in non-small cell lung cancer.

Background: Real-world treatment practices for positive mediastinal nodal disease in non-small cell lung cancer (NSCLC) continues to vary despite guidelines. We aim to assess national trends in the treatment of pathologic-N2 disease, and evaluate the association with clinical nodal staging and timing of systemic therapy. Methods: The National Cancer Database was queried for patients with NSCLC who underwent lobectomy and had pathologic-N2 disease from 2010-2017. National Comprehensive Cancer Network (NCCN) guideline concordance was evaluated. cN2 patients were analyzed based on timing of systemic therapy and response. Multivariable logistic regression evaluated outcomes by type of systemic therapy. Survival analysis utilized Cox proportional hazards regression and Kaplan-Meier methods. Results: 10,225 patients met inclusion criteria. Fifty-four percent of patients were understaged prior to surgery as either cN0 or cN1. Of clinically staged N2 patients, 56% received NCCN recommended neoadjuvant therapy. Annual guideline concordance increased until 2016 to a max of 62.9%. Neoadjuvant and adjuvant systemic therapy showed an overall survival benefit compared with no systemic therapy (HR 0.54 & 0.57), but no difference when compared against each other. Complete response after neoadjuvant therapy was associated with improved survival (5-year OS 56.1%, P<0.001), while partial response, no-response, and adjuvant therapy were similar. All systemic treatment strategies improved survival compared with no systemic therapy (5-year OS 24.5%). Conclusions: Guideline concordance for treatment of cN2 disease has been increasing, but still not followed in over 1/3 of patients. Responsiveness to neoadjuvant therapy appears to be a predictor of survival, and may become a prognostic adjunct for determining which patients would benefit from additional systemic therapy.