Role of Pathological Single- and Multiple-N Descriptors in Resected Non-small Cell Lung Cancer

Abstract

BackgroundThe 8th edition of lung cancer N staging assignment includes the location of lymph node metastasis, but does not include single- and multiple-N descriptors. Research QuestionDo the single- and multiple-N statuses stratify the prognosis of patients with non-small cell lung cancer (NSCLC)? Study Design and MethodsUsing the National Cancer Database, we analyzed patients with pathologically staged N1–2 NSCLC. N descriptors were classified into pathological single N1 (pSingle-N1), pathological multiple N1 (pMulti-N1), pSingle-N2, and pMulti-N2. Survival analysis was performed using Kaplan–Meier method and multivariate Cox regression models. ResultsIn the general analysis cohort, 24,531, 22,256, 8,528, and 21,949 NSCLC patients had pSingle-N1, pMulti-N1, pSingle-N2, and pMulti-N2, respectively. Patients with pMulti-N1 and pMulti-N2 had a shorter survival than those with pSingle-N1 and pSingle-N2, respectively (hazard ratio [HR]: 1.22, P < 0.0001 for N1 and 1.39, P < 0.0001 for N2). After adjusting age, sex, and histology, the HR for pSingle-N2 compared with pMulti-N1 was 1.05 (P = 0.0031). Patients with pN1 were categorized by metastatic lymph node count (1, 2, 3, 4+), showing significant prognostic differences among groups (P < 0.0001). In the sensitivity analysis cohort (limited to R0 resection, lobectomy or more, survival ≥ 30 days, ≥ 10 examined lymph nodes, and without neoadjuvant therapy; n = 34,904) and the external validation cohort (n = 708) analyses supported these results. InterpretationNSCLC patients with 1 metastatic lymph node, whether in N1 or N2 stations, had better survival than those with more than 1 lymph node involved. NSCLC patients with a single skip N2 lymph node metastasis had survival similar to patients with multiple N1 lymph nodes, and the number of lymph nodes involved in N1 resections up to ≥ 4 was sequentially prognostic.