Prognostic value of pathologic complete response to preoperative chemotherapy in early-stage non small cell lung cancer: Combined analysis of two IFCT randomized trials.

7057 Background: Our study aimed to evaluate whether pathologic complete response (pCR) in early-stage non-small cell lung cancer (NSCLC) following neoadjuvant chemotherapy resulted in improved outcome and to determine predictive factors for pCR. Methods: Eligible patients with stage IB or II NSCLC were included in two consecutive Intergroupe Francophone de Cancérologie Thoracique (IFCT) phase III trials evaluating platinum-based neoadjuvant chemotherapy, with pCR defined by the absence of viable cancer cells in the resected surgical specimen. Results: Among the 492 patients analyzed, 41 (8.3%) achieved pCR. In the pCR group, 5-year overall survival (OS) was 80.0% compared to 55.8% in the non-pCR group (p=0.0007). In multivariate analyses, pCR was a favorable prognostic factor of OS (RR=0.34; 95% CI=0.18-0.64) in addition to squamous cell carcinoma (SCC), weight loss ≤5%, and stage IB disease. Five-year disease-free survival (DFS) was 80.1% in the pCR group compared to 44.8% in the non-pCR group (p<0.0001). Two patients (4.9%) in the pCR group experienced disease recurrence compared to 193 patients (42.8%) in the non-pCR group. SCC subtype was the only independent predictor of pCR (OR=4.30; 95% CI=1.90-9.72). Conclusions: Our results showed that pCR after preoperative chemotherapy was a favorable prognostic factor in Stage IB-II NSCLC. Our study is the largest published series evaluating pCRs following preoperative chemotherapy. The only factor predictive of pCR was SCC. Identifying molecular predictive markers for pCR may help in distinguishing patients likely to benefit from neoadjuvant chemotherapy and in choosing the most adequate preoperative chemotherapy regimen.