Prognostic value of lymph node ratio after induction therapy in stage IIIA/N2 non-small cell lung cancer: a monocentric clinical study.

Abstract

The optimal treatment modalities for patients with stage IIIA N2 non-small cell lung cancer (NSCLC) are still a matter of debate. To provide best outcome and to avoid unnecessary treatment patient selection for surgical therapy is crucial. In addition to mediastinal downstaging the lymph node ratio (LNR) has been suggested as a prognosticator in this patient group. We retrospectively reviewed clinical and histopathologic data of 78 patients with stage IIIA N2 NSCLC, who underwent induction therapy with two cycles of platinum-based chemotherapy for intended surgery at our clinic between 2009 and 2016. To evaluate the prognostic value of the LNR the cut off was set at 0.33 as reported in prior literature. The median follow-up time was 30.1 months. In multivariate analysis mediastinal down staging was associated with a longer overall survival (OS): 52.2 (range, 5.9-89.7) months for ypN0 versus 24.6 (4.4-84.2) months for ypN1/2 (HR, 2.76; 95% CI, 1.07-7.1, P=0.0348). LNR ≤0.33 was linked to a better OS of 39.3 (range, 5.9-89.7) months compared to 14.7 (range, 4.4-66.2) months for a LNR >0.33 in univariate analysis (P=0.037). In multivariate analysis a statistical trend could be observed (HR, 2.82; 95% CI, 0.98-8.14, P=0.1). In patients with persistent lymph node involvement the LNR could also identify a subgroup of patients with a favorable prognosis (30.1 vs. 14.7 months, P=0.145). Mediastinal downstaging remains the best prognosticator in stage IIIA N2 NSCLC after induction therapy. However, using the LNR in patients with persistent mediastinal lymph node metastasis a subgroup with a favorable prognosis could be identified. The LNR could aid in finding the best treatment modalities for these patients.