Implications of Pathologic Complete Response Beyond Mediastinal Nodal Clearance With High-Dose Neoadjuvant Chemoradiation Therapy in Locally Advanced, Non-Small Cell Lung Cancer

Purpose: To determine, in a retrospective analysis of a large cohort of stage III non-small cell lung cancer patients treated with curative intent at our institution, whether having a pathologic complete response (pCR) influenced overall survival (OS) or freedom from recurrence (FFR) in patients who underwent definitive (≥60 Gy) neoadjuvant doses of chemoradiation (CRT). Methods and Materials: At our institution, 355 patients with locally advanced non-small cell lung cancer were treated with curative intent with definitive CRT (January 2000-December 2013), of whom 111 underwent mediastinal reassessment for possible surgical resection. Ultimately 88 patients received trimodality therapy. Chi-squared analysis was used to compare categorical variables. The Kaplan-Meier analysis was performed to estimate OS and FFR, with Cox regression used to determine the absolute hazards. Results: Using high-dose neoadjuvant CRT, we observed a mediastinal nodal clearance (MNC) rate of 74% (82 of 111 patients) and pCR rate of 48% (37 of 77 patients). With a median follow-up of 34.2 months (range, 3-177 months), MNC resulted in improved OS and FFR on both univariate (OS: hazard ratio [HR] 0.455, 95% confidence interval [CI] 0.272-0.763, P =.004; FFR: HR 0.426, 95% CI 0.250-0.726, P =.002) and multivariate analysis (OS: HR 0.460, 95% CI 0.239-0.699, P =.001; FFR: HR 0.455, 95% CI 0.266-0.778, P =.004). However, pCR did not independently impact OS (P =.918) or FFR (P =.474). Conclusions: Mediastinal nodal clearance after CRT continues to be predictive of improved survival for patients undergoing trimodality therapy. However, a pCR at both the primary and mediastinum did not further improve survival outcomes. Future therapies should focus on improving MNC to encourage more frequent use of surgery and might justify use of preoperative CRT over chemotherapy alone.