Management of challenging radioiodine treatment protocols: a case series and review of the literature

Abstract

Purpose: Radioactive iodine therapy with ¹³¹I is standard of care for treatment for many patients with differentiated thyroid cancer. Typically, ¹³¹I is administered as a pill, and much of its radioactivity gets excreted via the urine. This can present challenges in patients who are unable to swallow pills, absorb iodine via the gastrointestinal tract, or eliminate radioiodine via the urine (i.e. dialysis patients and patients with renal failure). In this case series, we present three cases in which the standard ¹³¹I treatment protocol for thyroid cancer could not be executed due to these challenges, and discuss the strategies to overcome these challenges. Results: Case 1 was a 4-year-old male with Noonan syndrome, dysphagia, and metastatic papillary thyroid cancer. He was unable to swallow the standard ¹³¹I pill due to the dysphagia. After a multi-disciplinary discussion between healthcare staff, a joint decision was made to proceed with liquid ¹³¹I therapy. The system, which was used to orally administer 75 mCi (2775 MBq) of Na¹³¹I in a liquid form, involved a vial provided to allow for mixing in grape juice. Case 2 was a 45 year-old male patient with significant scleroderma, severe gastric motility disorder, and papillary thyroid carcinoma. His severe gastric motility and malabsorption disorder precluded oral treatment due to risks of vomiting. Per discussions and collaborations with the patient’s gastroenterologist, the decision was made to proceed with intravenous ¹³¹I therapy, which was successfully performed after approval from the Radiological Health Branch of California. Case 3 was a 59 year-old male patient on hemodialysis with diabetes, hypertension, and follicular thyroid cancer. The challenge, in addition to waste disposal and dosimetry, was ensuring radiation protection for everyone present, given the risks of occupational exposures from radioactive iodine contaminating the dialysis machine. The radiation safety team monitored all healthcare workers and equipment involved, as per a joint decision by healthcare providers. Additionally, the planned dose was reduced from 50 mCi (1850 MBq) to 30 mCi (1110 MBq). None of the cases reported further disease progression since ¹³¹I treatment. Conclusion: These cases highlight unique challenges that can be encountered during radioactive iodine administration and approaches that can overcome these challenges. We conclude that provider collaboration and treatment customization are critical to overcome patient-specific challenges.