The proportion of patients with well-differentiated thyroid cancer who received radioactive iodine following total thyroidectomy increased significantly since 1990, and there is wide variation in the use of adjuvant radioactive iodine, according to a study in the Journal of the American Medical Association. Patients and tumor characteristics accounted for 21.1% of the variation and hospital type, and case volume accounted for 17.1%. “After adjusting for available patient, tumor, and hospital characteristics, 29.1% of the variance was attributable to unexplained hospital characteristics,” investigators from the University of Michigan reported.
The investigators analyzed data from a cohort of 189,219 patients with well-differentiated thyroid cancer treated at 981 hospitals associated with the U.S. National Cancer Database. Between 1990 and 2008, the proportion of patients receiving radioactive iodine after total thyroidectomy increased from 40.4% to 56% (P < .001). For tumors from 1.1 to > 4 cm, the percentage of patients treated with radioactive iodine increased from 55% to 67%. The proportion of smaller tumors treated with radioactive iodine “was lower but has also increased steadily over time,” the authors stated.
Multilevel analysis for patients treated between 2004 and 2008 showed “younger age and absence of comorbidity were associated with a small but significantly greater likelihood of receiving radioactive iodine after total thyroidectomy.” Female sex, African-American race, and lack of private or government insurance were associated with significantly less likelihood of receiving radioactive iodine. The researchers also found a statistically significant difference in radioactive iodine use between American Joint Committee on Cancer stages I and IV, but not for stage II or III vs stage IV. Analyses of hospital case volume showed that radioactive iodine was more likely to be used as the volume of thyroid cancer cases treated increased.
Interpreting the Results
“Even with the limitations inherent in a large database, the results of this study have implications for patients, physicians, and payers,” the authors wrote. “There is a clear role for adjuvant therapy with radioactive iodine in iodine-avid, advanced-stage, well-differentiated thyroid cancer; however, there is unclear benefit to radioactive iodine use in low-risk disease because patients with low-risk disease have an excellent prognosis regardless of intervention.”
In addition to cost savings associated with not using radioactive iodine for low-risk thyroid cancer, limiting the use of radioactive iodine would decrease the risk of adverse effects. “Not only are there transient adverse effects on quality of life with the hypothyroidism typically required before radioactive iodine treatment, but radioactive iodine itself has long-term health risks,” they stated.
“In the interests of curbing the increasing health care costs and preventing both overtreatment and undertreatment of disease,” the authors concluded, “indications for radioactive iodine should be clearly defined and disease severity should become the primary driver of radioactive iodine use.”
Haymart, et al: JAMA 306:721-728, 2011.