Predictive value of highly sensitive basal versus stimulated thyroglobulin measurement in long-term follow-up of thyroid cancer

Abstract

Objective: Recurrence of differentiated thyroid cancer (DTC) is associated with reduced quality of life, and therefore, early identification of patients at risk is urgently needed. Here we investigated the predictive power of various cut-off val ues of single stimulated thyroglobulin (s-Tg) and single highly sensitive measured, unstimulated thyroglobulin (u-hsTg) measurements close to the end of primary therapy for recurrence-free survival (RFS) in long-term follow-up (>10 years) of patients with DTC. Methods: In DTC patients with adjuvant radioiodine therapy, we assessed retrospectively u-hsTg (6 ± 3 months before s-Tg measurement) and s-Tg measurements (≤24 months after last radioiodine therapy). Positive predictive (PPV)/negative predictive values (NPV) of various cut-off values (s-Tg: 0.5/1.0 ng/mL; u-hsTg: 0. 09/0.2 ng/mL) for patient outcomes as well as additional factors associated with disease development were analyzed. Results: In total, 175 patients were retrospectively reviewed (tumor rec urrence: n = 14/ complete remission: n = 161). Examined cut-off values for s-Tg and u-hsTg showed significant predictive power for RFS (log-rank: all P 10 years of follow-up, both s-Tg and u-hsTg have a compar ably high predictive power for RFS, while only u-hsTg was significantly as sociated with a recurrence event. Serial u-hsTg measurements seem warranted since patients with tumor recurrence during follow-up may have an undetectable tumor marker at basel ine.

Keywords

• thyroid cancer
• stimulated thyroglobulin
• highly sensitive thyroglobulin measurement
• unstimulated thyroglobulin
• recurrence-free survival