RT Journal Article
SR Electronic
T1 Unexplained Hyperthyroglobulinemia in Differentiated Thyroid Cancer Patients as an Indication for Radioiodine Adjuvant Therapy: A Prospective Multicenter Study
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 62
OP 68
DO 10.2967/jnumed.120.243642
VO 62
IS 1
A1 Lin Cheng
A1 Ri Sa
A1 Qiong Luo
A1 Hao Fu
A1 Yuchen Jin
A1 Linglin Tang
A1 Yi Yang
A1 Chunjing Yu
A1 Libo Chen
YR 2021
UL http://jnm.snmjournals.org/content/62/1/62.abstract
AB The management for totally thyroidectomized differentiated thyroid cancer (TT-DTC) patients with unexplained hyperthyroglobulinemia remains indeterminate because of evidence scarcity. This multicenter study aimed at prospectively evaluating the response to radioiodine (131I) adjuvant therapy (RAT) and its potential role in risk stratification and causal clarification. Methods: TT-DTC patients with stimulated serum thyroglobulin levels greater than 10 ng/mL but no structurally evident disease were consecutively enrolled in 5 tertiary-care institutions. After the administration of 5.55 GBq of 131I, the risk of persistent, recurrent, or metastatic differentiated thyroid cancer (prmDTC) was compared with that before RAT. The causes of hyperthyroglobulinemia were explored—and the response to RAT assessed—6–12 mo after RAT. The change in suppressed thyroglobulin level was reported. Results: A cohort of 254 subjects with a median stimulated thyroglobulin level of 27.1 ng/mL was enrolled for the analyses. Immediately after RAT, low, intermediate, and high risk were identified in 5.9%, 88.6%, and 5.5% patients, respectively, with no significant difference in risk stratification compared with that before RAT (P = 0.952). During the follow-up (median, 10.6 mo), hyperthyroglobulinemia was ultimately attributed to a thyroid remnant, biochemical disease, and structural or functional disease in 17.3%, 54.3%, and 28.4% of subjects, respectively. In addition, responses that were excellent, indeterminate, biochemically incomplete, and structurally or functionally incomplete were achieved in 18.1%, 27.2%, 36.2%, and 18.5% of patients, respectively. Notably, the distribution for either cause of hyperthyroglobulinemia or response to RAT was comparable among the 3 postoperative risk groups. Suppressed thyroglobulin levels in patients who merely received RAT declined significantly over time. Conclusion: Our study demonstrated that over 90% of TT-DTC patients with unexplained hyperthyroglobulinemia are stratified as being at intermediate to high risk, and RAT using 5.55 GBq of 131I reveals biochemical, functional, or structural disease and yields a non–structurally or –functionally incomplete response in more than 80% patients, suggesting that TT-DTC patients with unexplained hyperthyroglobulinemia are explicit candidates for RAT.