According to a study in the August 17 issue of JAMA, despite uncertainty about the appropriate use of radioactive iodine after surgery for different stages of thyroid cancer, its use has increased between 1990 and 2008 among patients with all tumor sizes and there was wide variation in use of this treatment among hospitals.
Yearly more than 40,000 people in the United States are diagnosed with thyroid cancer. The vast majority of cases are well-differentiated thyroid cancer for which a thyroidectomy is the standard treatment. According to background information in the article, radioactive iodine is often administered after a total thyroidectomy to ensure full eradication of remnant thyroid tissue and to treat residual disease in patients with visible, inoperable, iodine-avid metastases.
Previous studies revealed a higher rate of survival and reduced tumor recurrence in patients with advanced-stage, well-differentiated thyroid cancer who were treated with radioactive iodine.
According to the authors,
"In contrast, for very low-risk disease, in which prognosis is typically excellent, treatment with radioactive iodine is of uncertain benefit."
Researchers Megan R. Haymart, M.D., of the University of Michigan, Ann Arbor, Mich., and their colleagues carried out a study to assess changes in practice patterns regarding the use of radioactive iodine following thyroidectomy and examined the degree to which hospitals vary in their use of radioactive iodine. The research involved 189,219 patients with well-differentiated thyroid cancer who were treated at 981 hospitals associated with the U.S. National Cancer Database between 1990 and 2008.
Research revealed a significant increase across all tumor sizes, in the proportion of patients with well-differentiated thyroid cancer who received radioactive iodine as therapy after total thyroidectomy during this time period.
Whilst 1,373 (40.4 percent) of 3,397 patients received radioactive iodine in 1990, the numbers rose to 11,539 (56.0 percent) of 20,620 patients respectively in 2008. The research suggested, that younger patients and those without comorbidity were linked to a small but remarkably higher likelihood of receiving radioactive iodine after total thyroidectomy. Female African Americans and patients without private/government insurance were linked to having significantly lower chances of receiving radioactive iodine.
The researchers also discovered 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. An analysis into hospital case volume revealed that the likelihood of radioactive iodine use increased as the volume of thyroid cancer cases treated at a hospital increased.
The authors comment,
"Wide variation in radioactive iodine use existed, and only 21.1 percent of this variation was accounted for by patient and tumor characteristics. Hospital type and case volume accounted for 17.1 percent of the variation. After adjusting for available patient, tumor, and hospital characteristics, 29.1 percent of the variance was attributable to unexplained hospital characteristics. This finding suggests disease severity is not the sole determinant of radioactive iodine use."
"... the results of this study have implications for patients, physicians, and payers. Although it is appropriate therapy for certain well-differentiated thyroid cancers, the benefit of radioactive iodine may not always exceed the risks. 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 clear cost-saving benefits associated with not using radioactive iodine for low-risk disease, limiting radioactive iodine use would decrease patients' risks 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."
The authors add, that the
"fact that disease severity appears to have a small influence on radioactive iodine use after thyroid surgery is concerning. In the interest of curbing the increasing health care costs and preventing both over-treatment and under-treatment of disease, indications for radioactive iodine should be clearly defined and disease severity should become the primary driver of radioactive iodine use."
Written by Grace Rattue