Precise Guidance of Adaptive Radiotherapy for Nasopharyngeal Carcinoma

This is an observational cohort study designed to (1) evaluate whether Gallium-68 (68Ga)-labeled fibroblast activation protein inhibitor ligand LM3 (68Ga-FAPI-LM3) positron emission tomography/computed tomography (PET/CT) improves the accuracy of nasopharyngeal carcinoma (NPC) staging, and (2) determine whether Gallium-68-labeled programmed death-ligand 1 (68Ga-PD-L1) PET/CT imaging parameters can provide early prediction of response to neoadjuvant immunotherapy. The study will assess the sensitivity and specificity of each tracer for staging and for predicting therapeutic response, analyze changes in tumor uptake parameters on 68Ga-FAPI-LM3 and 68Ga-PD-L1 PET/CT before and after treatment, and compare treatment efficacy and survival outcomes between patients with different degrees of residual PET uptake and between those who did and did not receive neoadjuvant immunotherapy. The primary question it aims to answer is: Does 68Ga-FAPI-LM3 PET/CT improve the accuracy of NPC staging, and can 68Ga-PD-L1 PET/CT imaging parameters provide an early prediction of response to neoadjuvant immunotherapy? Participants will be patients with biopsy-proven nasopharyngeal carcinoma who undergo 68Ga-FAPI-LM3 and/or 68Ga-PD-L1 PET/CT as part of clinical care or a research protocol. Tumor uptake metrics (e.g., maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic/volumetric indices) will be measured pre- and post-treatment; diagnostic performance (sensitivity, specificity) and associations between uptake changes and clinical outcomes (response rates, progression-free and overall survival) will be calculated.