Underlying Problems in Surgical Treatment of cT1-2N1 Non-Small Cell Lung Cancer.

 Obtaining an accurate preoperative diagnosis of N1 in non-small cell lung cancer (NSCLC) is a major difficulty. The aim of this retrospective study was to evaluate the pathological and long-term outcomes of NSCLC patients clinically staged with N1 disease, to aid in the search for better treatment strategies.  We retrospectively reviewed the clinical records of 1,180 consecutive patients with NSCLC who underwent surgery for curative intent from 1991 to 2011 in our department. Data on 96 (8.1%) patients who had cT1-2N1 disease and underwent lobectomy or more extensive surgery were available.  Only 32% of patients ( = 31) were confirmed to have pathological N1 disease, and 34 and 33% of patients were proven to have pN0 and pN2 disease, respectively. Female gender, ≤ 30 pack-year tobacco smoking history, adenocarcinoma, and left-sided disease were significantly associated with pathological upstaging ( test). Multivariate analysis using logistic regression revealed left-sided disease to be independently associated with upstaging (relative risk 4.00,  = 0.015). Left-sided disease was more likely to be underestimated by clinical N staging than right-sided disease ( test,  = 0.0001). Univariate and multivariate survival analyses demonstrated that left-sided disease was an independent prognostic factor associated with poor outcomes (Cox proportional hazards regression: hazard ratio 2.27,  = 0.037).  The diagnostic accuracy of clinical N1 status was poor. Left-sided disease appeared to be understaged by the preoperative assessment of N status, and therefore, patients who might benefit from preoperative induction treatment would not receive it.