Predictors for hilar/intrapulmonary lymph node metastasis in discrete type of clinical N1 non-small cell lung cancer

Objective Accurate preoperative evaluation of lymph nodes can provide optimal treatment for patients. However, in patients with clinical N1 disease (cN1) non-small cell lung cancer (NSCLC), no suitable predictor has been identified for hilar/intrapulmonary lymph node metastasis (pathological N1 disease; pN1). The purpose of this study was to identify pN1 in cN1 NSCLC patients. Methods We retrospectively reviewed the clinicoradiological features of 109 patients with a discrete type of cN1 NSCLC who had undergone complete resection at our institution from 2004 to 2015. The association between clinicoradiological variables and nodal status was analyzed to identify predictors for pN1. Results The cohort consisted of 77 males and 32 females, ranging in age from 39 to 84 years. The breakdown by pathological N category was 40 (37%) pN0, 41 (38%) pN1, and 28 (25%) pN2 patients. Maximum lymph node diameter was identified as a significant predictor for pN1, with an odds ratio of 1.25 (P = 0.010). When limited to 63 patients who underwent positron emission tomography (FDG-PET) at our institution, the maximum standardized uptake value (SUVmax) of the lymph node was an independent predictor, with an odds ratio of 1.91 with logistic regression analysis (P = 0.004). The size of lymph node and the SUVmax were significant factors for pN1, with optimal cut-off values of 13 mm and 4.28, respectively. Conclusions Among the patients with cN1, maximum lymph node size and SUVmax of the FDG-PET were significant predictors for pN1.