A two-center study in recurrent or metastatic nasopharyngeal carcinoma found that baseline 18F-FDG PET/CT metabolic parameters can predict survival, with whole-body total lesion glycolysis highlighted as a key metric. Patients in the study received PD-1 inhibitors and chemotherapy, linking metabolic imaging risk stratification to outcomes within an immunochemotherapy setting. Separately, a pooled retrospective analysis reported that fluorine-18 DCFPyL PET/CT detected recurrent prostate cancer in a substantial fraction of patients even at ultra-low PSA levels, pointing to the continued value of sensitive PET tracers for earlier detection. Together, the studies reinforce PET-based quantitative biomarkers as practical tools for patient selection and prognostication—especially in settings where disease burden is heterogeneous and treatment decisions need objective baseline anchors.