Clinical outcome of patients with differentiated thyroid cancer and raised anti thyroglobulin antibody levels: a retrospective study

Thyroglobulin (Tg) is a tumour marker seen in differentiated thyroid carcinoma (DTC). It becomes unreliable in the presence of an anti thyroglobulin antibody (TgAb). The purpose of the study was to examine the long-term results of DTC patients with increased TgAb levels. In a retrospective investigation, we included patients with DTC who had elevated TgAb levels after complete thyroidectomy. Patients with persistently elevated Tg (1 ng/ml) or radioiodine avid disease were omitted. Serial TgAb levels, excellent response (ER), incomplete response (IR), and anatomical recurrence were evaluated. The study involved 76 patients in total. Patients with IR had higher baseline TgAb (1071.27 ± 1216.17 vs. 99.61 ± 91.29 IU/ml, p< 0.001) and central compartment lymph node metastases (70.8% vs.46.4%, p= 0.035) in comparison to those in the ER group. In the first follow-up, 64 (84.2%) patients had a stable or fall in the TgAb (0 to−98.3%). Sixty-eight patients received high-dose radioiodine therapy (RIT). Out of these, 59 (86.5%) had transient, and 51 (75%) had a long-term fall in TgAb. After a follow-up period of 58.74 ± 26.26 months, 63.2% (48 out of 76) patients had IR. Nine (11.8%) patients had a rising TgAb level (3.7–170.9%) from baseline. Eleven patients had ¹⁸F-FDG PET/CT scans, and five had metabolically active recurrent disease. Three individuals had cervical lymph nodes removed. During the study, no patients died. High post-operative TgAb levels and lymph node metastases in the central compartment are risk factors for IR. In these patients, RIT causes a considerable decrease in TgAb. A low level of elevated TgAb is associated with a favourable outcome. Patients with recurrences had very high baseline TgAb >1000 IU/ml. Increased TgAb was not linked to higher mortality rates, but rather with positive clinical outcomes. (author)