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?

Summary Objective In view of the low probability of recurrence, the cost‐effective follow‐up of patients with papillary thyroid carcinoma ( PTC ) of low or intermediate risk and excellent response to initial therapy represents a challenge. This study evaluated the cases of structural recurrence among these patients. Patients The sample comprised 578 patients with PTC of low or intermediate risk, who were submitted to total thyroidectomy with or without 131 I therapy and exhibited an excellent response to initial therapy defined based on nonstimulated thyroglobulin (Tg) ≤0·2 ng/ml and negative neck ultrasonography ( US ). Results Twelve patients (2%) showed structural recurrence. At the time when recurrence was ‘confirmed’, Tg elevation had not occurred in only two patients, one with lymph node metastases <1 cm detected by US and the other with pulmonary metastases. Antithyroglobulin antibodies (TgAb) were undetectable in both patients. The first alteration observed in patients with recurrence was Tg elevation in six patients, Tg elevation associated with suspicious US in three, and suspicious US in two. An increase in TgAb was not the first alteration in any of the patients. Among the 560 patients who continued to have Tg ≤ 0·2 ng/ml, US permitted the detection of only one neck recurrence. Measurement of TgAb did not detect any recurrence. Conclusion Our results confirm that in patients with PTC of low or intermediate risk an excellent response to initial therapy can be defined based on nonstimulated Tg ≤ 0·2 ng/ml. Follow‐up consisting only of clinical examination and periodic measurement of Tg with a second‐generation assay may be sufficient.