Metabolic response evaluated by ¹⁸F-FDG PET/CT as a potential screening tool in identifying a subgroup of patients with advanced non-small cell lung cancer for immediate maintenance therapy after first-line chemotherapy

Purpose: Among patients with advanced non-small cell lung cancer (NSCLC), identification of a subgroup of patients for immediate maintenance treatment after first-line chemotherapy has great importance in improving survival. The purpose of this study was to investigate whether the metabolic responses evaluated by ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) may be a potential screening tool for identifying patients with early disease progression who may benefit from immediate maintenance treatment. Methods: A total of 52 patients with advanced NSCLC (36 men and 16 women, mean age 57.2 ± 10.6 years) who underwent baseline and follow-up ¹⁸F-FDG PET/CT after four cycles of first-line chemotherapy were enrolled. Maximum standardized uptake value (SUV_max), SUV _peak, metabolic tumour volume (MTV) and total lesion glycolysis (TLG) of the tumour lesions were measured and percentage decrease of the parameters was calculated. The prognostic significance of percentage decrease of these parameters and other clinical variables related to progression-free survival (PFS) and overall survival (OS) were assessed by Cox proportional hazards regression analysis. Receiver-operating characteristic (ROC) curve analysis was used to define the optimal cut-off value of percentage decrease of the parameters that could distinguish between early (PFS < 6 months) and late (PFS ≥ 6 months) disease progression groups. Results: Multivariate analysis showed that percentage decrease of TLG [hazard ratio per 10 % decrease = 1.030, 95 % confidence interval (CI) = 1.012-1.048, p = 0.001) was a significant predictor of PFS and OS. ROC curves identified a 50.0 % decrease in TLG as the optimal cut-off value to distinguish disease progression groups. Positive and negative predictive values of the optimal TLG value for selecting patients with late disease progression were 36.4 and 100.0 %, respectively. Conclusion: The percentage decrease in TLG of measurable tumour lesions may be a potential parameter to appropriately identify a subgroup of patients for immediate maintenance treatment after first-line chemotherapy in patients with advanced NSCLC.