Adjuvant Radioactive Iodine Use Among Differentiated Thyroid Cancer Patients in the Military Health System

Objective: Adjuvant radioactive iodine (RAI) for the treatment of differentiated thyroid cancer has been associated with better prognosis, but no consensus has been reached on the best practices for RAI. Limited data on RAI use and factors associated with the receipt of postoperative RAI in the general population are available and, to our knowledge, no data on RAI use among the U.S. Department of Defense (DoD) beneficiaries. Methods: Among 3,002 beneficiaries with differentiated thyroid cancer, who underwent total/near-total thyroidectomy between 1998 and 2007, logistic regression identified factors associated with RAI and examined effect modification by age and tumor size. Results: Fifty-two percent of patients received RAI. Receipt of RAI was more likely among beneficiaries who were diagnosed between 2004 and 2007, active duty members, had indirect care, and more advanced disease, and less likely among those affiliated with the Air Force or had unknown medical coverage. In addition, receipt of RAI significantly varied by tumor size among patients with regional lymph node metastasis. Conclusion: Among DoD beneficiaries, adjuvant RAI use was associated with clinical and nonclinical factors. Although evidence of effect modification between the recipient of RAI by tumor size was apparent, future research with a larger sample size is warranted to confirm results of this study.