Integrating pretreatment 18F-FDG PET-CT parameters, peripheral blood indicators and clinical characteristics in predicting chemotherapy plus immunotherapy outcomes for de novo metastatic nasopharyngeal carcinoma

Background: To develop a prognostic nomogram based on pretreatment 18F-FDG PET-CT radiomics parameters, peripheral blood indicators and clinical characteristics for risk stratification in patients with de novo metastatic nasopharyngeal carcinoma (dmNPC) receiving immunochemotherapy. Methodology: The eligible patients were randomly divided into training (n=183) and validation (n=79) cohorts. Least absolute shrinkage and selection operator regression was used for variable selection. Multivariate Cox regression analysis was performed to identify independent prognostic factors for progression-free survival (PFS). The predictive accuracy and discriminative ability of the nomogram were determined with a concordance index (C-index) and calibration curve. Results: Multivariate Cox analysis suggested that total lesion glycolysis, number of metastases, Epstein–Barr virus DNA, N-stage, lactate dehydrogenase, and total bilirubin were independent predictors of PFS and were used to develop a nomogram that could classify patients into low- and high-risk groups. The C-index of the nomogram for predicting disease progression was 0.75, which was significantly higher than the C-indices of the TNM stage and EBV DNA. The patients were then stratified into low- and high-risk groups based on the calculated scores. The median PFS was significantly higher in the low-risk group than in the high-risk group. Conclusions: The proposed nomogram with PET-CT parameters, peripheral blood indicators and clinical characteristics resulted in accurate prognostic prediction for patients with dmNPC receiving chemotherapy plus PD-1 inhibitors and could provide risk stratification for these patients.