Real-World Data Confirms 1-Year Serum Thyroglobulin Levels as Reliable for Thyroid Cancer Follow-Up

The study, known as the ITCO Real-World Analysis, underscores the continued efficacy of using 1-year serum Tg measurements and introduces refined Tg cutoffs to guide clinical decision-making for patients who have undergone total thyroidectomy with or without radioiodine remnant ablation (RRA).

Thyroglobulin, a protein produced by thyroid cells, is a key biomarker used in the follow-up of thyroid cancer patients. Elevated levels of Tg can indicate residual or recurrent disease, making accurate monitoring critical for effective management. Tg use for monitoring differentiated thyroid cancer (DTC) patients is well-established. Despite advancements with third-generation immunoassays that enhance accuracy, challenges remain, such as interference from anti-Tg antibodies and measurement variability. As treatment approaches evolve, there is a growing need to reassess Tg thresholds to ensure optimal patient management.

Against the above background, Giorgio Grani, Dept. of Translational and Precision Medicine, Sapienza University of Rome, Rome, Italy, and colleagues aimed to evaluate the performance of serum Tg testing in two populations: patients receiving total thyroidectomy and RRA, or treated with thyroidectomy alone.

For this purpose, the researchers conducted a prospective observational study using data from centers contributing to the Italian Thyroid Cancer Observatory (ITCO) database. The study included 540 patients with five years of follow-up who tested negative for anti-Tg antibodies. Serum thyroglobulin (Tg) levels were assessed at the 1-year follow-up visit. The main outcome measure was detecting structural disease within five years of follow-up.

The study led to the following findings:

• After excluding 26 patients with structural disease detected at any time point, the median Tg did not differ between patients treated with or without radioiodine.
• Data-driven Tg thresholds were established based on the 97th percentile of Tg levels in disease-free individuals: 1.97 ng/mL for patients undergoing thyroidectomy alone (lower than proposed by the MSKCC protocol and ESMO Guidelines, yet demonstrating good predictive ability, with a negative predictive value (NPV) of 98%) and 0.84 ng/mL for patients receiving post-surgical RRA.
• High sensitivity and NPV supported the potential of these thresholds in excluding structural disease.

"This real-world study confirms the ongoing reliability of 1-year serum Tg levels for monitoring. The proposed data-driven Tg thresholds offer significant insights, enhancing clinical decision-making for patients who have undergone total thyroidectomy, with or without radioiodine remnant ablation," the researchers concluded.

Reference:

Grani, G., Puxeddu, E., Morelli, S., Arvat, E., Nervo, A., Spiazzi, G., Rolli, N., Zatelli, M. C., Ambrosio, M. R., Ceresini, G., Marina, M., Mele, C., Aimaretti, G., Santaguida, M. G., Virili, C., Crescenzi, A., Palermo, A., Giaccherino, R. R., Meomartino, L., . . . Durante, C. Data-Driven Thyroglobulin Cutoffs for Low- and Intermediate-Risk Thyroid Cancer Follow-Up: ITCO Real-World Analysis. The Journal of Clinical Endocrinology & Metabolism. https://doi.org/10.1210/clinem/dgae559