Predicting clinical outcomes of patients with serum thyroglobulin antibodies after thyroidectomy for differentiated thyroid cancer: a retrospective study from a UK regional center.

Background: Twenty-twenty-five percent of patients with differentiated thyroid cancer (DTC) can have elevated thyroglobulin antibodies (TgAb). The study aimed to find any prognostic significance of elevated TgAb during follow-up.

Methods: Ten-year retrospective study from a tertiary center including 79 patients with raised TgAb after total/staged thyroidectomy for DTC. We identified patients with stable (7.6%), increasing (15%) and decreasing levels of TgAb (77.2%); groups 1, 2 and 3 respectively. During follow-up we analyzed TgAb in subcategories by TgAb trend (>50% rise, <50% rise, >50% decline, <50% decline, positive to negative/normalization, negative to positive and stable levels), gender, age, surgery, autoimmune disease, histology, RAI uptake, distant metastases, and recurrence.

Results: The incidence of raised TgAb levels was 33.2%, with female predominance. No connection was identified regarding other parameters. 11.4% had distant metastases. The highest mean maximum levels of TgAb was in group 2 (1918.75 IU/mL) and the lowest in group 3 (412.70 IU/mL). The recurrence rate changed significantly between the 3 groups: 50% in group 1, 75% in group 2, and 25% in group 3 (P=0.002). Recurrence rates decreased to 15% in the subcategory where TgAb became negative/normal from positive (P=0.0001). In patients with a negative to positive TgAb level trend or >50% rise, recurrence rates were 100% (P=0.041) and 70% (P=0.012) respectively.

Conclusions: Patients with increasing TgAb levels during follow-up have a higher rate of recurrence, distinctly for those with negative to positive trend and >50% rise in TgAb. These patients need closer follow-up, and TgAb may be used as a dynamic follow-up marker.