Prognostic value of post-ablation stimulated thyroglobulin in differentiated thyroid cancer patients with biochemical incomplete response: a bi-center observational study.

Abstract

Little is known regarding parameters predicting persistence/recurrence for differentiated thyroid cancer (DTC) patients exhibiting biochemical incomplete response (BIR) to initial therapy. High post-ablation stimulated thyroglobulin (ps-Tg) levels have undetermined prognostic significance in DTC patients with BIR. The goal of this bi-center study was to systemically assess the prognosis of DTC patients with BIR in relation to ps-Tg levels and to establish the determinants of clinical outcomes. The retrospective study of consecutive 81 DTC patients from two tertiary centers who were classified as BIR after total thyroidectomy and radioiodine ablation between January 2010 to December 2019 were analyzed. BIR was defined as ps-Tg > 10 ng/mL measured under thyroid hormone withdrawal at 9-12 months followed by radioiodine ablation, negative anti-Tg antibodies, and no structural evidence of disease. Multivariable regression models were used to evaluate potential risk factors associated with clinical outcomes. With a median follow-up of 5.4 years, 28 patients (34.6%) showed no evidence of disease and 50 patients (61.7%) were of a biochemical persistent status at the time of final follow-up. Conversely, 3 patients (3.7%) developed structural evidence of disease. Ps-Tg of 20.2 ng/mL or greater displayed the high positive predictive value (81%) for disease persistence/recurrence. Multivariate analysis revealed that only a high ps-Tg level (>20.2 ng/mL) was an independent risk factor for persistent/recurrent disease (odds ratio = 5.6; p < 0.001). The ps-Tg (>20.2 ng/mL) was a valuable predictor of disease persistence/recurrence in DTC patients with BIR.