Postoperative stimulated thyroglobulin level and recurrence risk stratification in differentiated thyroid cancer

Postoperative preablative stimulated thyroglobulin (ps-Tg) has been evaluated in predicting prognosis and success of ablation regarding differentiated thyroid cancer (DTC); however, its relationship with recurrence risk and radioiodine decision-making remains uncertain, especially in Chinese DTC patients. We aimed to evaluate the association between ps-Tg and recurrence risk stratification in DTC, to provide incremental values for ps-Tg in postoperative assessment and radioiodine management.

Seven hundred and seven patients with DTC were included; low-risk (L; n = 90), intermediate-risk (I; n = 283), and high-risk (H; n = 334, 117 with distant metastasis [M1]) patients were divided according to recurrence risk stratification. The M1 group was further analyzed regarding evidence of metastasis. Cut-off values of ps-Tg were obtained using receiver operating characteristic analysis.

Patients with more advanced disease at initial risk stratification were more likely to have higher ps-Tg levels (I vs. L: P < 0.05; H vs. I: P < 0.001; H vs. L: P < 0.001). The corresponding cut-off value of ps-Tg for distinguishing sensitivity and specificity in each of the two groups was 2.95 ng/ml (I vs. L: 61.5%, 63.3%), 29.5 ng/ml (H vs. I: 41.9%, 92.6%), 47.1 ng/ml (M1 vs. M0 in the H group: 79.5%, 88.9%) and 47.1 ng/ml (M1 vs. M0 in all patients: 79.5%, 93.7%). With the cut-off value at 47.1 ng/ml, ps-Tg was the only factor that could be used to identify distant metastases, and consequently if measured before radioiodine therapy would prevent 10.26% of patients with M1 from undertreatment.

Ps-Tg, as an ongoing reassessment marker, favors differential recurrence risk grading and provides incremental values for radioiodine treatment decision-making.