the utility of quantitative 18f-fdg pet/ct-derived parameters as prognostic factors for predicting overall survival in radioiodine-refractory differentiated thyroid cancer

Objective(s): this study investigates the relationship between quantitative 18f-fdg pet/ct metabolic parameters and overall survival (os) in patients with radioiodine-refractory differentiated thyroid cancer (rai-r dtc).methods: we conducted a prospective analysis of 127 patients with rai-r dtc. quantitative metabolic parameters including suvmax, suvmean, suvpeak, total metabolic tumor volume (mtv), and total lesion glycolysis (tlg) were assessed in 18f-fdg -avid recurrent or metastatic lesions via 18f-fdg pet/ct imaging. patients were monitored for disease progression and mortality for at least one-year post pet/ct imaging. receiver operating characteristic (roc) curves were used to establish cut-off values for predicting 5-year mortality, while the kaplan-meier method estimated the 5-year survival rate. univariate and multivariate cox regression analyses identified prognostic factors associated with os.results: the metabolic parameters derived from 18f-fdg pet/ct demonstrated high sensitivity and specificity for predicting 5-year os. roc curve analysis established optimal cut-off values for suvmax (20.27 g/ml), suvmean (7.46 g/ml), suvpeak (7.8 g/ml), tlg (45.74 g/ml×cm³), and mtv (5.78 cm3) (auc: 0.82, 0.78, 0.82, 0.82, and 0.86, respectively; p<0.001). kaplan-meier analysis revealed significantly lower os in patients with higher values of these parameters compared to those with lower ones (survival rates: 42.1% vs. 95.6%, 65.5% vs. 96%, 52.3% vs. 96.3%, 46.5% vs. 97.3%, and 57.3 % vs. 98.3%, respectively; p<0.001). univariate cox regression identified suvmax, suvmean, suvpeak, tlg, and mtv as significant predictors of 5-year os (p<0.05). in multivariate analysis, suvpeak and mtv emerged as independent predictors of os.conclusion: quantitative 18f-fdg pet/ct-derived parameters are significant predictors of 5-year os, exhibiting high sensitivity and specificity. elevated values of these parameters correlate with increased mortality rates. our findings suggest that suvpeak and mtv are independent prognostic factors for 5-year os in patients with radioiodine-refractory dtc.