Significance of smoking history and FDG uptake for pathological N2 staging in clinical N2-negative non-small-cell lung cancer

Background: This study was conducted to evaluate whether smoking history and the standardized uptake value (SUV) of 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) uptake are associated with unexpected pathological N2 status (pN2) in non-small-cell lung cancer (NSCLC). Patients and methods: We analyzed the data of 220 patients who underwent surgical resection with clinical N2-negative status on computed tomography (CT) and positron emission tomography (PET)‐CT. The maximum SUV of primary tumor was chosen for logistic analysis. Results: Seventy-two patients (33%) had never smoked. The SUV ranged from 1.0 to 29.0 (median 9.1). In univariate analysis, adenocarcinomas (P = 0.019), female gender (P = 0.010), N1 on CT (P = 0.025), and N1 PET‐CT (P = 0.001) were associated with a high probability of pN2. The proportion of pN2 in never smokers was higher than in ever smokers (26% versus 10% respectively; P = 0.002). The SUV remained on a multivariate logistic model (odds ratio 1.1; 95% confidence interval 1.0‐1.2; P = 0.010) and it had a better predictive value in never smokers than in ever smokers (P = 0.017). Conclusions: This study indicates an association between smoking history and pN2 in clinically negative N2 NSCLC. The different roles of FDG uptake were also suggested based on smoking history.