A Patient with Papillary Thyroid Carcinoma and Biochemical Evidence of Disease at Follow-Up Visits and Increasing Serum Tg Values at the Follow-Up Assessments

Abstract

Persistently detectable serum thyroglobulin (Tg) without residual normal thyroid after a total thyroidectomy for papillary thyroid carcinoma (PTC) indicates biochemically persistent disease, even in patients without detectable lesions on imaging studies. Increasing serum Tg levels reflect progression of the disease. For distant organ metastases, radioactive iodine (RAI) therapy followed by thyroid-stimulating hormone (TSH) suppression is the first-line treatment. No effective therapies had been available for RAI-refractory metastases. Molecular-targeted agents appeared recently as a new modality for RAI-refractory metastases. However, it is difficult to decide whether and when such agents should be administered in individual patients. An evaluation of the progressiveness of the disease is important in making this treatment decision, as are changes in serum Tg levels. A short Tg-doubling time (Tg-DT) is a very strong predictor both of carcinoma recurrence and carcinoma-related death superior to the conventional factors. Patients with a Tg-DT <1 year are likely to die of carcinoma, while metastases are not immediately life threatening for those with a Tg-DT >2 years. We must carefully weigh the advantages and disadvantages of using molecular-targeted agents, because they usually are associated with severe adverse events.