Predictive value of TgAb for disease status in differentiated thyroid cancer patients with stimulated Tg<1 μg/L during postoperative assessment / 中华核医学与分子影像杂志

ABSTRACT

Objective:To analyze the association between thyroglobulin antibody (TgAb) and differentiated thyroid cancer (DTC) metastases detected by post-radioactive iodine (RAI) therapy scan, when stimulated thyroglobulin (sTg) <1 μg/L.Methods:A total of 314 (68 males, 246 females, age (44.5±12.5) years) post-thyroidectomy DTC patients whose sTg <1 μg/L between March 2013 and May 2017 in Henan Cancer Hospital were enrolled retrospectively. Patients underwent 131I whole-body planar imaging ( 131I-WBS) and SPECT/CT imaging 5 d after 131I administration. Iodine avid metastases were compared between TgAb-positive group and TgAb-negative (TgAb<4 kU/L) group. Logistic regression analysis was conducted to assess odds ratio ( OR) for iodine avid metastases in each subgroup (Q1 4 kU/L≤TgAb≤9.27 kU/L; Q2 9.27 kU/L<TgAb≤26.75 kU/L; Q3 26.75 kU/L<TgAb≤101.43 kU/L; Q4 TgAb>101.43 kU/L) of TgAb-positive patients, with the TgAb-negative patients as the reference. χ2 test was used to analyze the data. Results:Iodine avid metastases were found in 16.9% (53/314) of DTC patients and were more frequently in TgAb-positive group with TgAb>26.75 kU/L than TgAb-negative group (26.0%(19/73) vs 13.7%(23/168); χ2=5.382, P=0.02). Most metastases (92.5%, 49/53) occurred in cervical and mediastinal lymph nodes. The OR for iodine avid metastases was obviously high in TgAb-positive patients with 26.75 kU/L<TgAb≤101.43 kU/L ( OR(95% CI) 3.687(1.397-9.733), P=0.008) and with intermediate-high risk of recurrence ( OR(95% CI) 2.489(1.169-5.301), P=0.018), with the TgAb-negative group as the reference. Conclusion:The possibility of functional metastasis should be fully considered during 131I therapy in TgAb-positive DTC patients after surgery who have higher TgAb level and risk stratification, even if sTg<1 μg/L.