Low postoperative nonstimulated thyroglobulin as a criterion for the indication of low radioiodine activity in patients with papillary thyroid cancer of intermediate risk ‘with higher risk features’

Abstract

We conclude that in intermediate-risk patients 'with higher risk features', low nonstimulated Tg measured with a second-generation assay can be used as criterion for the administration of low (131) I activities (1850 MBq or less).

Can the follow‐up of patients with papillary thyroid carcinoma of low and intermediate risk and excellent response to initial therapy be simplified using second‐generation thyroglobulin assays?

“…In patients with PTC of low or intermediate risk submitted to total thyroidectomy who do not have circulating TgAb or neck US abnormalities, nonstimulated Tg ≤ 0·2 ng/ml measured with a second‐generation assay, instead of stimulated Tg < 1–2 ng/ml, has been accepted for the definition of an excellent response to initial therapy . In fact, previous studies have shown that stimulated Tg > 1–2 ng/ml is uncommon in patients with nonstimulated Tg ≤ 0·2 ng/ml and that the risk of recurrence is low in these individuals . However, stimulated Tg was obtained in most of the studies.…”

“…Patients followed up at our institution from 2007 to 2013, who met the following criteria, were selected: (i) diagnosis of PTC (except for microcarcinoma restricted to the thyroid or the noninvasive encapsulated follicular variant), (ii) classified as low or intermediate risk according to the American Thyroid Association, (iii) submitted to total thyroidectomy with or without adjuvant therapy with 131 I, and (iv) excellent response to initial therapy (nonstimulated Tg ≤ 0·2 ng/ml, undetectable TgAb and neck US showing no abnormalities 12–18 months after thyroidectomy) …”

“…In patients with papillary thyroid carcinoma (PTC) of low or intermediate risk submitted to total thyroidectomy, followed or not by adjuvant therapy with 131 I, an excellent response to initial therapy can be defined by the combination of nonstimulated thyroglobulin (Tg) ≤0·2 ng/ml measured with a second‐generation assay, absence of antithyroglobulin antibodies (TgAb), and neck ultrasonography (US) showing no abnormalities . Considering the increasing availability of second‐generation Tg assays, this definition based on nonstimulated Tg will probably be more used than the traditional criterion based on stimulated Tg ≤ 1–2 ng/ml.…”

“…The long‐term follow‐up of those patients represents a challenge. The cost of detecting each recurrence can be high because of the low frequency of recurrence . In addition, there is the possibility of false‐positive results, with negative psychological repercussions for the patient, and the need for exam repetition and even invasive procedures.…”

Ablative Radioiodtherapie des Schilddrüsenkarzinoms

“…Die gleiche Autorengruppe präsentierte eine zweite prospektive Studie mit 102 Patienten bei gleichem Risikoprofil, aber veränderten Bedingungen im Ausgangspunkt und im Endpunkt (31). Ausgangspunkt war das nicht-stimulierte Tg < 0,3 ng/ml vor der I-131 Ablation, Endpunkt ein nicht-stimuliertes Tg ≤ 0,2 ng/ml, entsprechend einer "exzellenten Response" nach ATA-Kriterien.…”