P1.03-073 Predictors for Pathological N1 and N2 Disease in Clinical N1 Non-Small-Cell Lung Cancer

Abstract

Patients with clinical N1 (cN1) non-small-cell lung cancer (NSCLC) is usually considered to be candidates for curative resection. However, they sometimes have unexpected mediastinal nodal involvement (pN2). To avoid futile pulmonary resection, accurate preoperative evaluation of nodal status would be necessary. The purpose of this study was to identify predictors for lymph node metastasis in cN1 NSCLC patients. We retrospectively reviewed data on the clinicopathological and radiological features of 170 patients with cN1 NSCLC who had undergone complete resection at Nagoya University Hospital between 2004 and 2015. Hilar and/or intrapulmonary lymph nodes with ≥ 1.0 cm in the short axis on computed tomography or with high accumulation of [18F] Fluorodeoxyglucose (FDG) in positron emission tomography compared with that of the adjacent mediastinal tissue were considered as cN1 in our institution. The association between clinicoradiological variables and nodal status was analyzed to identify predictors for lymph node metastasis. The cohort consisted of 125 males and 45 females, ranging in age 39 to 84 years. There were 62 (36%) adenocarcinomas, 82 (48%) squamous-cell carcinomas, 10 (6%) large-cell carcinomas, and 16 (10%) other types of cancers. The breakdown by pathological N category was 61 (36%) pN0, 72 (42%) pN1, and 37 (22%) pN2 patients. Among pN2 patients, only three showed negative N1 lymph nodes (skip pN2 metastasis). Female gender, adenocarcinoma histology, middle or lower lobe origin and positive N1 lymph node (pN1) were significantly associated with pN2 by univariate analysis. Logistic regression analysis showed that the female and pN1 were significant predictor for pN2 with the odds ratio of 3.0 and 13.1, respectively (P = 0.02 and 0.0001, respectively). In addition, using the 63 patients extracted from our cohort of this study, we sought the predictor of pN1. The maximum size of the lymph node and standardized uptake value of the FDG were significant factor for pN1 with the cut-off value of 1.3 cm and 4.28, respectively. Female gender and pN1 was significantly associated with pN2 in cN1 NSCLC patients of our cohort. The large size and a high accumulation of FDG of hilar or intrapulmonary lymph node might predict the pN1.