Should 'low-risk' thyroid cancer patients with residual thyroglobulin be re-treated with iodine 131?
OBJECTIVE
The American consensus statement on patients with low-risk thyroid cancer, published in 2003, suggests repeat (131)I therapy if the thyroglobulin value is elevated at first follow-up. We evaluated this strategy in our practice.


METHODS
Among 407 patients with thyroid cancer who had total thyroidectomy and (131)I ablation between January 2000 and December 2003, 12 patients with stage I thyroid cancer (any tumour (T), any node (N), metastasis (M)0 if < 45 years or T1, N0, M0 if > 45 years), were re-treated on the basis of their thyroglobulin level at first follow-up. Mean patient age was 32.8 years. None of them had a T4 tumour. Thyroglobulin levels after thyroid hormone withdrawal 'off-T4' ranged between 4.5 and 251 ng/ml (median 8). One to four courses of 3.7 GBq (131)I were given.


RESULTS
Three patients had a negative (131)I therapy scan and an uneventful course. Two patients had slight residual uptake only in the thyroid bed and negative ultrasound examination. Four patients had isolated (131)I uptake in the mediastinal region. No abnormalities were found on complementary mediastinal imaging. This finding was interpreted as benign (131)I thymic uptake. The last three patients also had mediastinal thymic uptake associated with a slight thyroid bed uptake. One patient had a gradual increase in the thyroglobulin level, and underwent resection of nonfunctioning neck lymph nodes. Thyroglobulin levels declined in all other patients.


CONCLUSIONS
No distant lesions were found in a group of young 'low-risk' thyroid cancer patients given empirical (131)I therapy for residual thyroglobulin. When blind (131)I therapy shows no uptake, or uptake limited to the thymus, (131)I therapy should not be repeated. The authors also briefly discuss the hypothesis that enhanced thymus might be a source of benign thyroglobulin secretion.
Hindié
Elif
E
Department of Nuclear Medicine, Hôpital Saint-Antoine, Assistance Publique Hopitaux de Paris, Paris, France. elif.hindie@sls.aphp.fr
Zanotti-Fregonara
Paolo
P
Duron
Françoise
F
Keller
Isabelle
I
Bouchard
Philippe
P
Devaux
Jean-Yves
JY
D000328:Adult; D015415:Biomarkers / Q000097:blood; D002291:Carcinoma, Papillary / Q000097:blood* / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D037981:Neck Dissection; D009367:Neoplasm Staging; D018579:Patient Selection; D011446:Prospective Studies; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D019233:Retreatment; D018570:Risk Assessment / Q000379:methods; D013950:Thymus Gland / Q000000981:diagnostic imaging / Q000378:metabolism; D013954:Thyroglobulin / Q000097:blood* / Q000378:metabolism; D013964:Thyroid Neoplasms / Q000097:blood* / Q000532:radiotherapy* / Q000601:surgery; D013965:Thyroidectomy; D014915:Whole-Body Counting
D015415:Biomarkers; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D013954:Thyroglobulin