Table 3.

Definition and initial management of radioiodine therapy-refractory differentiated thyroid carcinoma

Recommendations
• A negative Dx-WBS or pT-WBS is not sufficient to classify a patient as RaIT-refractory.
• The quality of the various assessments performed should always be carefully checked.
• Patients with ≥1 negative lesion on Dx-WBS should not be considered refractory but should receive local treatment for WBS-negative lesions and RaIT for RAI-avid lesions.
• Assessment of structural response to treatment should not strictly adhere to the RECIST criteria but should be individualized by taking into account patient clinical status and wishes.
• The overall course of serum Tg levels should be evaluated, not absolute Tg levels.
• The duration of response to treatment should be recorded (<6 months or >12 months, or in between).
• The overall amount of 131I-RAI activity administered should be monitored.
• The frequency and severity of adverse events should be recorded.
• The cumulative administered 131I-RAI activity being above the suggested limit is not sufficient to define a patient as having RaIT-refractory disease.

Dx-WBS diagnostic WBS, pT-WBS post-therapy WBS, RAI radioiodine, RaIT radioiodine therapy, RECIST Response Evaluation Criteria In Solid Tumors, Tg thyroglobulin, WBS whole-body scan