In properly selected patients with differentiated thyroid cancer, antithyroglobulin antibodies decline after thyroidectomy and their sole presence should not be an indication for radioiodine ablation

Abstract

Objective: Our objective was to evaluate the trend of antithyroglobulin antibodies (TgAb) during follow-up of patients with differentiated thyroid cancer (DTC) treated without RAI, as well as their role in the risk of recurrence. Subjects and methods: This was a prospective, descriptive study. A total of 152 consecutive patients with DTC treated in a single institution undergoing total thyroidectomy without RAI and followed for a median of 2.3 years (0.5-10.3) were divided in two groups: TgAb(-) (n = 111) and TgAb(+) (n = 41). Patients were classified according to AJCC 7 th and 8 th editions, as well as to their risk of recurrence and response to treatment categories. Results: Both groups, TgAb(-) and TgAb(+), were similar regarding patient and tumor characteristics. At the end of follow-up, 90 (59.2%), 57 (37.5%), 3 (2%) and 2 (1.3%) patients achieved excellent, indeterminate, biochemically incomplete and structurally incomplete response, respectively. The risk of structural recurrence was similar in both groups (TgAb[-] 0.9% vs. TgAb[+] 2.4%, p = 0.46). In the TgAb(+) group, TgAb became negative in 10 (24.4%), decreased ≥ 50% without negativization in 25 (60.9%), decreased < 50% in 4 (9.8%) and remained stable or increased in 2 (4.9%) cases. The only incomplete structural response had increasing TgAb during follow-up. Conclusions: In properly selected patients with DTC, TgAb concentration immediately after total thyroidectomy should not mandate RAI ablation, and their trend during follow-up may impact the risk of recurrence. Arch Endocrinol Metab. 2019;63(3):293-9

Warthin-like and classic papillary thyroid cancer have similar clinical presentation and prognosis

“…However, when subgroup analysis was performed and only patients with negative TgAb were included, the rates of excellent response were similar in WL-PTC and C-PTC. Moreover, we have previously reported that patients with PTC and positive TgAb, in whom their concentration decrease ≥ 50% and have a negative neck US during follow-up, have a risk of recurrence comparable to patients with excellent response (10). It is noteworthy that, in our present cohort, nearly a third of TgAb positive patients achieved this specific, excellent-like response, most of which remained free of disease even in absence of RAI ablation.…”

“…Incomplete structural response was defined as highly suspicious neck US (or any other image modality), confirmed with cytological study, regardless of Tg or TgAb serum concentration. Indeterminate response was defined either as (i) negative neck US plus Tg ≥ 0.2-≤ 1.0 ng/mL in RAI ablated or ≤ 5.0 ng/mL in non RAI ablated patients, plus TgAb(-) or (ii) negative US plus TgAb(+) with decreasing or stable concentration during follow-up (increase < 50% in their concentration) or (iii) nonspecific findings on imaging studies (10)(11)(12).…”

Prevalence and Clinical Significance of Preoperative Thyroglobulin Antibodies in Differentiated Thyroid Cancer Patients

“…Among the 54 preopTgAb positive patients, 34 patients had an excellent response and 15 patients had indeterminate responses, while the biochemically incomplete and structurally incomplete responses were observed in 3 and 2 patients, respectively. In a study by Zavala et al [23], 68.3% showed an indeterminate response followed by an excellent response in 24.4% of patients, biochemical incomplete in 4.9%, and structural incomplete in 1%. Ora et al [38] suggested that high postoperativeTgAb and lateral compartment metastasis are risk factors for the persistence of high TgAb levels and incomplete treatment response in long-term follow-up.…”

“…The following criteria were used to categorize treatment responses. Negative postoperative thyroglobulin and TgAb were considered as Excellent response, positive thyroglobulin or TgAb with an increase in concentration was considered an incomplete biochemical response, unchanged thyroglobulin or TgAb status was considered indeterminate, and highly suspicious status regardless of TgAb was considered incomplete structural response [23] [24].…”

TgAb’s Change Trend and Degree of Decline Has Good Prognostic Value for Preoperative TgAb-Positive DTC Patients: A Retrospective Study in Southwest China

“…Compared to observing TgAb at the single time-point, TgAb trends appear to have more clinical utility as a surrogate tumor marker in the surveillance of TgAb-positive DTC patients [14] , for that the trend of TgAb is reported to be associated with higher tumor metabolism [15] . Most existing literatures concluded that an increase in TgAb can indicate disease presence [16][17][18] , and some literatures empirically used a reduction of 50% of TgAb to group subjects, nding the reduction >50% can represent a good prognostic [19] . Based on these studies, our study described overall TgAb change trends after surgery for preoperative TgAb-positive DTC patients and compared different change trends between patients with different clinical outcomes, aiming at further elucidating the prognostic value of TgAb.…”