A low postoperative nonstimulated serum thyroglobulin level excludes the presence of persistent disease in low-risk papillary thyroid cancer patients: implication for radioiodine indication.
OBJECTIVE
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.


METHODS
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 (131) I 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 (131) I in these cases.
Postgraduate Program, Santa Casa de Belo Horizonte, Minas Gerais, Brazil.|Endocrinology Service, Santa Casa de Belo Horizonte, Minas Gerais, Brazil.
Pedro W
PW
Rosario
Postgraduate Program, Santa Casa de Belo Horizonte, Minas Gerais, Brazil.|Endocrinology Service, Santa Casa de Belo Horizonte, Minas Gerais, Brazil.
Gabriela F
GF
Mourão
Postgraduate Program, Santa Casa de Belo Horizonte, Minas Gerais, Brazil.
Thassio Leonardo
TL
Siman
Endocrinology Service, Santa Casa de Belo Horizonte, Minas Gerais, Brazil.
Maria Regina
MR
Calsolari
D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000097:blood; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D013954:Thyroglobulin / Q000097:blood*; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000097:blood; D055815:Young Adult
D007457:Iodine Radioisotopes; D013954:Thyroglobulin