ATA Guidelines Tools

10 Differentiated Thyroid Cancer 131 I Treatment Î 131 I is indicated for treatment of iodine-avid persistent locoregional or nodal disease that cannot be resected as well as known or presumed iodine-avid distant metastases. For patients with persistent disease following 131 I administration, the decision to pursue additional 131 I therapy should be individualized according to clinical data and previous response (Figures 3 and 4). The potential risks and benefits must be weighed on an individual basis. (B) Î In order to facilitate 131 I uptake by residual iodine-avid cancer, the TSH should be above 30 mIU/L. This can be achieved in almost all children by withdrawing LT4 for ≥14 days. In selected patients who cannot mount an adequate TSH response or cannot tolerate profound hypothyroidism, rhTSH may be considered. Low iodine diets have not been specifically evaluated in children but may enhance the effective radiation activity of 131 I and are recommended. (A) Î Adequate hydration should be ensured in all children receiving therapeutic 131 I to facilitate clearance of the radioisotope, and additional supportive care with antiemetic medications and stool softeners/laxatives should be considered. Sour candy or lemon drops can be given after 131 I treatment, but not all experts ascribe to this practice. (C) Î The routine use of lithium and amifostine cannot be recommended. (F) Î Based on the lack of data comparing empiric treatment and treatment informed by dosimetry, we are unable to recommend for or against either approach in most patients. Many experts provide the first activity of 131 I based on an empiric estimate and reserve dosimetry for patients with diffuse pulmonary metastases or subsequent activities of 131 I in patients with iodine-avid distant metastases who require additional therapy. However, dosimetry can be considered prior to the first 131 I treatment in small children and in patients with limited bone marrow reserve. Due to the differences in body size and iodine clearance in children compared with adults, it is recommended that all activities of 131 I should be calculated by experts with experience in dosing children. (I) Î A posttreatment WBS is recommended for all children 4-7 days after 131 I therapy. The addition of SPECT-CT may help to distinguish the anatomic location of focal uptake. (B) Î There are clear benefits and risks, both acute and chronic, following administration of 131 I during childhood. The challenge is to define those patients for whom the benefits of 131 I therapy outweigh the risks. Families should be provided full disclosure of the risks and benefits of 131 I and their opinion must be considered in the final decision. (C)

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