Prognostic Value of Stimulated Thyroglobulin Levels at the Time of Radioiodine Administration in Differentiated Thyroid Cancer

Abstract

Objective: The prognostic value of stimulated thyroglobulin (sTg) and Tg-related parameters prior to and immediately after radioactive iodine (RAI) administration was assessed in a cohort of patients presenting with differentiated thyroid cancer (DTC) as a predictor of recurrent or progressive structural disease. Methods: Clinical records of 180 DTC patients were retrospectively reviewed, and serum TSH, Tg, and Tg antibodies were recorded just before RAI administration (pre-) and at the time of whole body scanning (post-). Based on the results of initial staging and RAI scintigraphy, patients were divided into two groups: those who were considered to be structurally disease-free after thyroidectomy and RAI (group 1) and those who were not (group 2). Univariate analyses were performed for pre-Tg, ratioTg (post-Tg/pre-Tg), and other clinical and pathological markers for long-term outcome, as well as separate bivariate analyses focusing on pre-Tg to correct for possible confounders. Different pre-Tg cut-off values for predicting structural disease recurrence were assessed in a subgroup of patients in group 1 prepared with thyroid hormone withdrawal. Results: In group 1, (n = 166) male gender, higher T-stage and both Tg-related parameters proved to be significant risk factors for structural disease relapse. Of all candidate variables, only higher T-stage served to predict progressive structural disease in group 2 (n = 14). Subgroup analysis showed a negative predictive value of 91.67% for pre-Tg < 10 µg/L. Conclusion: The sTg value at the time of RAI administration may be helpful in predicting structural disease recurrence in patients with DTC.

Post-Surgical Indications to Radioiodine Treatment and Potential Risk Factors for Post-Treatment Recurrence in Patients with Intermediate-Risk Differentiated Thyroid Carcinoma

“…Pre-ablation-stimulated Tg is another independent predictive factor for the evidence of relapse at one-year follow-up. Supporting data for this are readily available in the literature, both in older studies which confirm pre-ablation-stimulated Tg combined with TgAb, post-ablation Tg and ATA risk, as an efficient tool in predict one-year relapse [ 31 ], and more recent research, which has associated the first post-surgery Tg detection with definite predictions of persistence and one-year recurrence, particularly in papillary microcarcinomas [ 32 ].…”

Analysis of factors influencing the clinical outcome after surgery and 131I therapy in patients with moderate-risk thyroid papillary carcinoma

“…Although postoperative serum Tg level can be a useful indicator of the possibility of remission, persistence, or recurrence of disease after the initial therapy, its predictive usefulness is affected by several variables, which include the duration after total thyroidectomy, residual thyroid tissues, and the serum TSH and TgAb levels (14,15). Moreover, there is no clear optimal ps-Tg cut-off point established yet for the prediction of 131 I therapeutic outcomes.…”

Impact of delayed radioiodine therapy in intermediate‐/high‐risk papillary thyroid carcinoma

“…After initial consideration of these features, postoperative disease status is a relevant consideration in postoperative treatment decision‐making. Postoperative serum Tg may be useful when assessing the persistence of disease or thyroid remnant and predicting potential future disease recurrence . In addition, RAI avidity can help in evaluating whether or not the target is amenable to RAIT .…”