Usefulness of Preradioactive Iodine Scans in Thyroid Cancer

There is an evolving role for radioactive iodine (RAI) in thyroid cancer treatment. Radioactive iodine treatment usually involves a pre-RAI whole-body iodine scan and a posttherapy scan. The clinical utility of pre-RAI therapy scans has been increasingly questioned.

To evaluate the clinical utility of pre-RAI whole-body iodine scans.

We retrospectively reviewed the medical records of differentiated thyroid cancer patients treated with RAI. Using records blinded for pre-RAI scans, 3 endocrinologists developed empiric RAI treatment plans for each patient based on surgical pathology. This was repeated using the unblinded records, and the treatment plans made with and without pre-RAI scan results were compared.

A total of 164 patients met the inclusion criteria: 89 patients (54.3%) were low risk, 61 (37.2%) intermediate risk, and 14 (8.5%) high risk for thyroid cancer recurrence. After blinded review, RAI treatment was recommended for 122 patients (74.3%); 46 were determined to be appropriate for a low-dose RAI, 75 a medium dose, and 1 a high dose. When unblinded, different recommendations were made for only 7 patients (5.7%), with 6 being recommended for a higher RAI dose. In addition, the prescan RAI results prompted recommendations for additional testing, such as neck ultrasounds or computed tomography or postoperative thyroglobulin levels. Pre-RAI scans affected patient care plans in only 7 (5.7%) of the 164 patients in the study.

In most patients with thyroid cancer who may need RAI, pre-RAI scans may not affect management, and empiric RAI doses may be a more cost-effective and convenient option.