Preablative Stimulated Thyroglobulin Correlates to New Therapy Response System in Differentiated Thyroid Cancer

Context: Studies suggested a potential value of preablative stimulated thyroglobulin (ps-Tg) on predicting the recurrent and persistent diseases of differentiated thyroid cancer, whereas its correlations with therapeutic response remain uncertain. Objective: To establish the correlation between ps-Tg and therapeutic response proposed in 2015 American Thyroid Association guidelines, and calculate a cutoff ps-Tg threshold for predicting a poor response. Design/Setting: Patients who underwent total thyroidectomy and radioactive iodine therapy in a university hospital participated in this retrospective study. Patients: Totally, 452 patients with differentiated thyroid cancer were followed for a median of 38 months and were divided into three groups in terms of ps-Tg level: group 1, less than 1 ng/ml (n = 82); group 2, 1-10 ng/ml (n = 173); and group 3, at least 10 ng/ml (n = 197). Main Outcome Measure: Clinical outcomes were assessed based on response to therapy restaging system, dividing responses into excellent, indeterminate, biomedical incomplete, and structural incomplete (SIR). Results: Therapeutic responses could be obviously distinguished by different ps-Tg strata. SIR was identified in none of group 1, 1.73% of group 2, and 42.74% of group 3, respectively (chi(2) = 123.037, P < .001). A cutoff value of ps-Tg at 26.75 ng/ml was obtained by receiver operating characteristic curve for differentiating SIR from either excellent, indeterminate, or biomedical incomplete responses. The area under curve was 0.947 and negative predictive value was 96.99%. Ps-Tg was an independent predictive variable of SIR (odds ratio, 42.312; P < .001). Conclusions: Ps-Tg has a great performance in predicting therapeutic response and providing incremental value for decision making of radioactive iodine therapy, especially for patients with high ps-Tg level.National Natural Science Foundation of China [81571714]SCI(E)PubMedARTICLElinys@pumch.cn31307-131310