Long-term consequence of elevated thyroglobulin in differentiated thyroid cancer.

Area of Science:

• Endocrinology
• Oncology
• Nuclear Medicine

Background:

• Serum thyroglobulin (Tg) is a key biomarker for differentiated thyroid cancer (DTC) recurrence.
• Assessing stimulated Tg (sTg) patterns in patients with no structural evidence of disease (NSED) is crucial for predicting clinical course.
• Imaging studies like US, PET, and CT aid in evaluating NSED in DTC patients.

Purpose of the Study:

• To evaluate the predictive value of sTg 1 year after treatment (sTg1) and subsequent sTg measurements for long-term outcomes in DTC patients.
• To determine if sTg patterns can predict structural recurrence and biochemical remission (BR).
• To analyze the relationship between initial sTg levels and the rate of BR or recurrence.

Main Methods:

• Retrospective analysis of 186 DTC patients treated with thyroidectomy and radioactive iodine ablation (1995-2004).
• Patients with NSED and sTg1 ≥2 ng/mL were categorized by sTg1 levels (Groups A, B, C) and by the percentage change in sTg2 (Groups 1 and 2).
• Serial sTg measurements were taken every 1-2 years until recurrence or BR.

Main Results:

• Patients in NSED showed decreasing sTg levels over time.
• Biochemical remission (BR) rates were 41% (Group A), 17% (Group B), and 1% (Group C), with significant differences between sTg1 groups and between Groups 1 and 2 (p<0.001).
• Structural recurrence rates also differed significantly among sTg1 groups (p=0.005) and between Groups 1 and 2 (p<0.001).

Conclusions:

• Elevated sTg1 levels and lack of sTg decrease predict a higher risk of recurrence.
• 41% of patients with sTg1 of 2-5 ng/mL achieved BR, highlighting the prognostic significance of this range.
• Repeated sTg measurements are essential for predicting prognosis in DTC patients.