Preablative stimulated thyroglobulin in predicting dynamic risk stratification after 1 year in patients with differentiated thyroid cancer

The aimThe aim of the study is to establish the utility of stimulated preablative stimulated thyroglobulin (ps-Tg) as a predictor of response to therapy and to determine a possible cut-off for ps-Tg as prognostic tool.Patients and methodsA total of 73 consecutive patients who underwent total thyroidectomy and remnant ablation with radioactive iodine therapy (RIT) were reviewed retrospectively. Patients were classified according to the dynamic risk stratification 1 year after initial treatment. The ps-Tg values were compared among the groups. ROC curve analysis was performed.ResultsThe mean age at diagnosis was 43.85 (range: 17–75) with a female-to-male ratio of 4.6. Ps-Tg value after total thyroidectomy and before RIT ranged from 0,1 to 256 ng/mL. When patients were restaged, 74% had excellent response to treatment, 12.3% indeterminate and 13.7% incomplete response 1 year after initial therapy. ROC curve analysis showed that the optimal cut-off for ps-Tg was 15 ng/mL with a sensivity of 61%; a specificity of 87%; PPV of 61% and NPV of 87%. Among the group of patients showing an excellent response to treatment after 1 year, 87% had ps-Tg < 15 ng/mL.ConclusionPs-Tg before RIT is associated with dynamic risk stratification at 1 year after therapy in patients with DTC. Higher ps-Tg levels were found in patients that had indeterminate, and particularly incomplete, response.