PUB004 Preoperative Therapy is Not Required for Clinically Occult N2 Non-Small Cell Lung Cancer

Abstract

Patients with clinically evident N2 NSCLC are usually treated by definitive chemoradiation or by resection following neoadjuvant therapy. To date, No clinical-trials compared survival differences between induction and adjuvant therapy for occult N2-disease. We tested the hypothesis that patients with occult-N2 have equivalent survival after either neoadjuvant or adjuvant therapy. A retrospective review of a prospective database (2005-2014) was performed to identify patients with CT/PET negative mediastinal nodes, who were subsequently found to have positive N2 nodes either by mediastinoscopy or after resection. Demographic, clinical, and pathological data were reviewed. Disease free survival (DFS) was analyzed using Kaplan-Meier and differences compared using log-rank. Cox proportional hazards regression analysis was performed to determine the independent predictors of DFS. Univariate predictors (p<0.20) were selected for inclusion in a multivariate model. Among 1693 patients with cN0-cN1 by PET/CT, 116 (6.8%) had pathologically confirmed N2 disease, of whom 101 had surgical resection. Fifty two patients had mediastinoscopy, of whom 20 (38%) were positive and received induction chemotherapy followed by surgical resection. Surgical resection followed by adjuvant chemotherapy was done in the remaining 81 patients. There was no difference between the induction and no induction groups in clinical variables (Table1), the number of positive mediastinal nodal stations (median 1 in both groups, p=0.605), or in 5 years DFS (31% vs. 36%, p= 0.644) (Fig1). In the multivariate model of the whole cohort, timing of chemotherapy (preoperative or adjuvant) was not associated with worse DFS, while increased clinical tumor size was the strongest predictor of worse DFS (HR:1.47, CI: 1.16-1.85, p= 0.001). Patients with NSCLC and clinically occult N2 by PET/CT maybe treated by primary surgical resection followed by adjuvant chemotherapy. Invasive mediastinal staging in this setting has a low sensitivity and is not necessary.