Prognostic Stratification of Stage IIIA-N2 Non–Small-Cell Lung Cancer After Induction Chemotherapy: A Model Based on the Combination of Morphometric-Pathologic Response in Mediastinal Nodes and Primary Tumor Response on Serial 18-Fluoro-2-Deoxy-Glucose Positron Emission Tomography

Abstract

Purpose Surgical resection in patients with stage IIIA-N2 non–small-cell lung cancer (NSCLC) is usually reserved for patients with mediastinal downstaging after induction chemotherapy (IC). However, clinical restaging is often inaccurate, and there are insufficient data to conclude that all patients with persistent mediastinal disease will not benefit from surgery, or that all patients with mediastinal clearance benefit from surgery. We created a data-based restaging strategy combining morphometric tissue analysis of mediastinal lymph nodes (LNs) and 18-fluoro-2-deoxy-glucose positron emission tomography (FDG-PET) response monitoring in the primary tumor. Patients and Methods Baseline and repeat FDG-PET after IC, as well as complete resection specimens of both mediastinal LNs and primary tumor, were available in 30 patients. Histologic response grading was performed by means of conventional morphometric procedures. Mediastinal response grading combined with the percentage decrease of maximum standardized uptake value (SUVmax) on the primary tumor was correlated with survival. Results Patients with persistent major mediastinal LN involvement have a 5-year overall survival rate of 0%. The 5-year overall survival rate for patients with cleared or persistent minor mediastinal LN involvement was significantly higher in patients with a more than 60% decrease in SUVmax on the primary tumor as compared with patients with a less than 60% decrease in SUVmax (62% v 13%; log-rank P = .002). Conclusion These data may suggest that (1) persistent mediastinal disease after IC does not always exclude favorable outcome after surgery; (2) serial FDG-PET may select surgical candidates among patients with mediastinal downstaging or persistent minor disease; (3) persistent major mediastinal disease has a poor prognosis and such patients should not be considered for surgery.