Prognostic value and optimal threshold of first thyroglobulin in low/intermediate risk DTC

Area of Science:

• Endocrinology
• Oncology
• Nuclear Medicine

Background:

• Differentiated thyroid cancer (DTC) management involves surgery and radio-iodine therapy (RIT).
• Assessing treatment response in low/intermediate risk DTC patients is crucial for prognosis.

Purpose of the Study:

• To determine the prognostic value of first thyroglobulin (fTg) levels.
• To establish the optimal fTg threshold before RIT for predicting treatment outcomes in DTC.
• To identify risk factors for incomplete treatment response.

Main Methods:

• Retrospective analysis of 383 DTC patients treated with surgery and RIT.
• Evaluation of treatment response at 1 and 2 years post-RIT.
• Receiver operating curve (ROC) analysis to determine optimal fTg cut-off values.

Main Results:

• An fTg level of ≥33.5 ng/mL and an fTg/TSH ratio of ≥0.36 were optimal for detecting incomplete response.
• fTg < 33.5 ng/mL demonstrated a 98.5% negative predictive value for excluding distant metastases.
• Patients with fTg ≥ 33.5 ng/mL experienced longer times to excellent response and required more treatments.

Conclusions:

• Elevated fTg (≥33.5 ng/mL) is the most significant predictor of treatment failure post-RIT in DTC.
• This threshold can inform treatment decisions and intensity adjustments for low/intermediate risk DTC patients.