Predictors for locoregional recurrence for clinical stage III-N2 non-small cell lung cancer with nodal downstaging after induction chemotherapy and surgery

Purpose: Pathologic downstaging following chemotherapy for stage III-N2 NSCLC is a well-known positive prognostic indicator. However, the predictive factors for locoregional recurrence (LRR) in these patients are largely unknown. Methods: Between 1998 and 2008, 153 patients with clinically or pathologically staged III-N2 NSCLC from two cancer centers in the United States were treated with induction chemotherapy and surgery. All had pathologic N0-1 disease, and none received postoperative radiotherapy. LRR were defined as recurrence at the surgical site, lymph nodes (levels 1-14 including supraclavicular), or both. Results: Median follow-up was 39.3 months. Pretreatment N2 status was confirmed pathologically (18.2 %) or by PET/CT (81.8 %). Overall, the 5-year LRR rate was 30.8 % (n = 38), with LRR being the first site of failure in 51 % (22/+99877943). Five-year overall survival for patients with LRR compared with those without was 21 versus 60.1 % (p < 0.001). Using multivariate analysis, significant predictors for LRR were pN1 disease at time of surgery (p < 0.001, HR 3.43, 95 % CI 1.80-6.56) and a trend for squamous histology (p = 0.072, HR 1.93, 95 % CI 0.94-3.98). Five-year LRR rate for pN1 versus pN0 disease was 62 versus 20 %. Neither single versus multistation N2 disease (p = 0.291) nor initial staging technique (p = 0.306) were predictors for LRR. N1 status also was predictive for higher distant recurrence (p = 0.021, HR 1.91, 95 % CI 1.1-3.3) but only trended for poorer survival (p = 0.123, HR 1.48, 95 % CI 0.9-2.44). Conclusions: LRR remains high in resected stage III-N2 NSCLC patients after induction chemotherapy and nodal downstaging, particularly in patients with persistent N1 disease.