Endocrine Abstracts

Background: In patients with papillary thyroid cancer (PTC), serum thyroglobulin (Tg) levels are monitored in order to detect disease recurrence. However, these patients may show anti-thyroglobulin antibodies (TgAb) in serum, which may influence the quantitation of Tg level and thus the confirmation of disease recurrence. The aim of this retrospective study was to show clinical outcome and the diagnostic strategy of recurrent or persistent PTC patients with high serum TgAb titer.

Subjects and methods: Details of 12 patients with recurrent or persistent PTC who had undergone total thyroidectomy and who had higher than normal TgAb titers at recurrence or during persistent disease were recorded in our thyroid cancer registry database. The clinical outcomes as well as the diagnostic approaches used to screen for cancer metastasis in these cases were reviewed.

Results: There were five women and seven men with a median age of 44 years old (range, 24–66 years). The median follow-up duration was 10.7 years (range, 0.3–21.6 years). Nine patients had recurrent PTC, and the other three had persistent disease. Five of the 12 patients had died of metastatic PTC during the follow-up period. Ten of the 12 patients had undetectable Tg levels at recurrence or during persistent disease. Thyroid ultrasonography is a reliable diagnostic tool for neck lymph node metastasis or local recurrence. Computed tomography revealed cancer metastases in ten patients, while I-131 scan failed to detect cancer metastases in three patients.

Conclusions: High serum TgAb titers in PTC patients at recurrence or during persistent disease may indicate disease progression and poor clinical outcome. Because serum Tg levels may fail as a surrogate tumor marker, a variety of imaging studies should be performed in order to screen for cancer metastasis and to initiate the aggressive treatment needed for these patients.