FDG-PET response predicts overall and disease free survival after induction chemotherapy of locally advanced (stage III) Non-Small Cell Lung Cancer (NSCLC)

Introduction: Pathologic response after induction therapy has shown to have a major impact on outcome. The non-invasive FDG-PET could predict tumor response in NSCLC (non-small cell lung cancer) and is a possible tool to identify potential candidates for cure in advanced NSCLC IIIA/IIIB after induction chemotherapy (CTx).

Methods: 47 patients with NSCLC IIIA/B were included in the study. Median age was 62 years; 83% were in stage IIIB according to UICC. PET was performed before and 3 weeks after 4 cycles Doxetacel and Carboplatin to calculate mean tumor index (MTI) from mean tumor diameter and standardised uptake value (SUV). Metabolic response (mean tumor index=MTI) was given as MTI-ratio (post/pre CTx). MTI-ratio ≤15% was defined as responder with metabolic complete remission (m-CR), MTI-R >15% as non responder (non-metabolic complete remission=non-m-CR). After resection, histopathological morphometry was analysed.

Results: 18 patients had m-CR, 29 had non-m-CR. Pathologic regression grades III (no vital tumor cells) or IIB (<10% vital tumor cells) have been proven in 56% of patients with m-CR. Overall median survival was 29.9 months, progression-free survival 21.4 months. Survival at 4 years is estimated at 68% and 14% (p=0.002) and progress-free survival at 64% and 9% (p=0.0005) for responder (m-CR) and non-responder (m-non-CR) patients, respectively.

Conclusion: Morphometric tumor response after induction chemotherapy correlates with metabolic remission by FDG-PET. Metabolic response is a strong predictor of progression free and overall survival. FDG-PET is an important non-invasive tool for management of patients with advanced lung cancer to predict survival and disease free survival.