Abnormal brain glucose metabolism patterns in patients with advanced non-small-cell lung cancer after chemotherapy:A retrospective PET study

Purpose: This study was designed to investigate the acute or chronic post-chemotherapy effect and different chemotherapy cycles effect on brain glucose metabolism.Methods: A total of seventy-three patients who received chemotherapy after being diagnosed with advanced non -small-cell lung cancer (NSCLC) and underwent F-18-Fluorodeoxyglucose positron emission tomography/ computed tomography (F-18-FDG PET/CT) scan at Nuclear Medicine Department of the Fifth Hospital of Sun Yat-sen University between September 2017 and August 2022 were included. Seventy-two healthy control patients who underwent whole-body F-18-FDG PET/CT scans at our department, without any evidence of malignancy and confirmed by follow-up visits, were included. Advanced NSCLC patients were classified into six arms: short-to -long course (chemotherapy cycles under 4, between 5 and 8 and more than 8) in acute chemotherapy effect (AC) group (scanned F-18-FDG PET/CT within 6 months post-chemotherapy) or chronic chemotherapy effect (CC) group (the interval between scanning and the last chemotherapy session more than six months). Statistical Parametric Mapping (SPM) analysis between patients' groups and healthy controls' brain F-18-FDG PET was performed (uncorrected p < 0.001 with cluster size above 20 contiguous voxels).Results: There were no significant differences between patients' groups and healthy controls in age, gender and body mass index (BMI). SPM PET analyses revealed anomalous brain metabolic activity in different groups (p < 0.001). Short-course + AC group exhibited hypermetabolism in the cerebellum and widespread hypometabolism in bilateral frontal lobe predominantly. Only hypometabolic brain regions were observed in middle-course + AC patients. Long-course + AC group displayed a greater number of abnormalities. Notably, these metabolic ab-normalities tended to decrease in CC groups versus AC groups across all courses.Conclusion: Our study revealed that patients with advanced NSCLC who underwent chemotherapy exhibited persistent abnormal brain metabolism patterns during continuous chemotherapy and these abnormalities tended to recover after completion of chemotherapy over time, but without correlation to an increasing number of chemotherapy cycles. F-18-FDG PET/CT may serve as a possible modality for evaluating brain function and guiding appropriate treatment timing.