Clinico-social factors to choose radioactive iodine dose in differentiated thyroid cancer patients: an Asian survey.

Objective: This survey was designed to investigate the practice of radioactive iodine (RAI) therapy and clinico-social factors related to RAI dose in differentiated thyroid cancer (DTC) patients among Asian countries.

Materials And Methods: A survey questionnaire was mailed to Asian Nuclear Medicine physicians that addressed the infrastructure, general regulations on RAI therapy, adherence to recommendations, RAI dose selection, factors to elevate RAI dose, and follow-up protocols in DTC patients. Contrived RAI practice recommendations were based on key international guidelines.

Results: A total of 38 institutes from 20 Asian countries were enrolled. Dose administration criterion was 30 mCi, but release criterion was variable (5-70 μSv/h). When the administered RAI dose was classified according to three risk stratifications, RAI dose distribution was variable, especially in the low-risk group. In this group, 14.0% of respondents preferred no ablation, 54.5% were treated with 0-30 mCi, 21.5% were treated with 30-50 mCi, and 10.0% were administered even higher doses of 80-100 mCi. The major factors that influenced the elevated RAI doses in the respondents included high serum thyroglobulin (Tg), inadequate information on lymph node involvement, and histopathology reporting. Although serum Tg measurement is included in most of the institutes as a follow-up tool, neck ultrasound was omitted in 25% and in another 25% a whole-body scan was not included.

Conclusion: Different RAI dose ranges are used in the low-risk group probably because the enrolled physicians consider RAI dose elevation on the basis of clinico-social factors beyond pre-existed guidelines. Our study may enable closer harmonization of RAI therapy practice in Asian countries.