To evaluate the presence of persistent disease, including on post-therapy whole-body scan (RxWBS), in low-risk patients with papillary thyroid carcinoma (PTC) >1 cm who have low nonstimulated thyroglobulin (Tg) (measured with a sensitive assay), negative anti-Tg antibodies (TgAb) and neck ultrasound (US) showing no metastases after total thyroidectomy.Patients
We studied 154 patients with PTC >1 cm classified as low risk, who had US without metastases, negative TgAb, nonstimulated Tg ≤ 0·25 ng/ml and TSH ≤2 mIU/l about 3 months after total thyroidectomy.Results
Tg measured immediately before 131I was ≤1 ng/ml in 89·5% of the patients and >1 ng/ml in 10·5%. None of the patients showed ectopic uptake on RxWBS. Uptake in the thyroid bed was observed in 146 (94·8%) patients and was ≤2% in all of them. In the control assessment 9–12 months after ablation, stimulated Tg (sTg) ≤1 ng/ml was achieved in 150 patients (97·4%). Only one patient had sTg >2 ng/ml (2·5 ng/ml) and none of the patients had apparent disease detected by imaging methods. During further short-term follow-up after control assessment (median of 24 months), none of the patients had tumour recurrence.Conclusions
The combination of nonstimulated Tg ≤0·25 ng/ml, negative TgAb and US without metastases after thyroidectomy rules out the presence of persistent disease (including on RxWBS) in low-risk patients with PTC >1 cm. This demonstration weakens the indication of ablation with 131I in these cases.