Size and extranodal extension of metastatic lymph nodes in lung adenocarcinoma

BACKGROUND: This study assessed the prognostic significance of metastatic lymph node size (MLNS) and extranodal extension (EN) in patients with node-positive lung adenocarcinoma (ADC). METHODS: Prognostic factors influencing survival were analyzed, including age, sex, extent of operation, T- and N-stage, size of tumor, postoperative chemotherapy, presence of EN, and MLNS (>7.0 vs. ≤7.0 mm). RESULTS: Three hundred seventy-five patients met the inclusion criteria were enrolled (mean age: 59.8±10.5 years). Increasing MLNS was significantly correlated with large tumor size (P=0.015), advanced N status (P<0.001), and presence of EN (P<0.001). In multivariable analysis, large tumor size [hazard ratio (HR) 1.135, 95% confidence interval (CI): 1.050 to 1.228, P<0.001], adjuvant chemotherapy (HR 0.582, 95% CI: 0.430 to 0.787, P<0.001), EN (HR 1.454, 95% CI: 1.029 to 2.055, P=0.034), and MLNS greater than 7 mm (HR 1.741, 95% CI: 1.238 to 2.447, P<0.001) were significant prognostic factors for survival. Patients were classified into 3 groups: Group A, MLNS ≤7.0 mm/EN (−); Group B, MLNS ≤7.0 mm/EN (+) or MLNS >7.0 mm/EN (−); and Group C, MLNS >7.0 mm/EN (+). The 5-year overall survival (OS) was 72.2%, 59.0%, and 38.5% in Groups A, B and C, respectively (P<0.001). CONCLUSIONS: The MLNS and presence of EN could provide an important prognostic implication for patients with node-positive lung ADC.