Radio-iodine therapy in differentiated thyroid cancer: indications and procedures.
Post-surgical ablative iodine-131 therapy is recommended for all differentiated thyroid cancer primary tumors>1 cm in diameter. Regarding smaller primary tumors, 131I ablation may be helpful in special cases: tumor close to the thyroid capsule, previous percutaneous radiation to the neck, familial occurrence of thyroid cancer, tumor diameter 5-10 mm, and unfavorable histological variants. In this context, the patient's preferences for safety should be considered. In most centers, standard fixed activities of 1-3 GBq are used for 131I ablation. Preparation for the procedure with such activities requires a low-iodine diet for 2-3 weeks and stimulation of thyroid stimulating hormone (TSH) by withholding of thyroid hormone for 3 weeks following thyroidectomy or by use of recombinant human TSH. The advantages of recombinant TSH are avoidance of hypothyroid morbidity and consequently a better quality of life, as well as a lower radiation dose to extra-thyroidal compartments. To treat metastastic differentiated thyroid cancer, higher activities of radio-iodine (in the range 4-11 GBq) are necessary; if possible, individual dosimetry is recommended. The standard approach to preparation for 131I therapy in patients with metastases is endogenous hypothyroidism after thyroid hormone withdrawal.
Reiners
Christoph
C
Department of Nuclear Medicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany. reiners@nuklearmedizin.uni-wuerzburg.de
Dietlein
Markus
M
Luster
Markus
M
D018265:Carcinoma, Papillary, Follicular / Q000532:radiotherapy*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D013963:Thyroid Hormones / Q000008:administration & dosage; D013964:Thyroid Neoplasms / Q000532:radiotherapy*
D007457:Iodine Radioisotopes; D013963:Thyroid Hormones