Background: Radioactive iodine (RAI) remnant ablation has been used to eliminate normal thyroid tissue and may also facilitate monitoring for persistent or recurrent thyroid carcinoma. The use of RAI for low-risk patients who we define as those under age 45 with stage I disease or over age 45 with stage I or II disease based on American Joint Committee on Cancer (AJCC) 6th edition, or low risk under the metastases, age, completeness of resection, invasion, size (MACIS) staging system (value <6) is controversial. In this extensive literature review, we sought to analyze the evidence for use of RAI treatment to improve mortality and survival and to reduce recurrence in patients of various stages and disease risk, particularly for those patients who are at low risk for recurrence and death from thyroid cancer.
Methods: A MEDLINE search was conducted for studies published between January 1966 and April 2008 that compared the effectiveness of administering versus not administering RAI for treatment of differentiated thyroid cancer (DTC). Studies were grouped A through D based on their methodological rigor (best to worst). An analysis, focused on group A studies, was performed to determine whether treatment with RAI for DTC results in decreased recurrences and improved survival rates.
Results: The majority of studies did not find a statistically significant improvement in mortality or disease-specific survival in those low-risk patients treated with RAI, whereas improved survival was confirmed for high-risk (AJCC stages III and IV) patients. Evidence for RAI decreasing recurrence was mixed with half of the studies showing a significant relationship and half showing no relationship.
Conclusions: We propose a management guideline based on a patient's risk-very low, low, moderate, and high-for clinicians to use when delineating those patients who should undergo RAI treatment for initial postoperative management of DTC. A majority of very low-risk and low-risk patients, as well as select cases of patients with moderate risk do not demonstrate survival or disease-free survival benefit from postoperative RAI treatment, and therefore we recommend against postoperative RAI in these cases.