Does Lymph Node Metastasis Have a Negative Prognostic Impact in Patients with NSCLC and M1a Disease?

OBJECTIVES: Patients with NSCLC with M1a disease regardless of lymph node status were categorized as stage IV. This study aims to investigate whether the N descriptors in M1a patients could provide clinical information.

METHODS: Overall, 39,731 patients with NSCLC with M1a disease were identified from the Surveillance, Epidemiology, and End Results database during 2005-2012. Lung cancer-specific survival (LCSS) was compared among M1a patients stratified by N stage. A Cox proportional hazards regression model was applied to evaluate the prognostic factors. Statistical analyses were performed in all subgroups.

RESULTS: M1a patients without lymph node involvement had the best LCSS, followed by patients with N1 disease; no difference in LCSS was observed between N2 and N3 disease (N0 versus N1, p < 0.001; N1 versus N2, p < 0.001; and N2 versus N3, p = 0.478). Similarly, this trend was observed when patients were subdivided into two temporal cohorts (2005-2008 and 2009-2012) and also when M1a disease was subdivided into contralateral pulmonary nodules and pleural dissemination (malignant pleural effusion [or pericardial effusion] and pleural nodules). In addition, a difference in LCSS between N2 and N3 disease was observed in patients with malignant pleural nodules (p = 0.003). Multivariate analysis showed that lymph node involvement was an independent prognostic factor for M1a patients, and this result was also noticed in all subgroups.

CONCLUSIONS: These results provide preliminary evidence that lymph node stage may have clinical significance among patients with NSCLC with M1a disease, adding prognostic information.