Despite uncertainty about the appropriate use of radioactive iodine after surgery for different stages of thyroid cancer, between 1990 and 2008 its use has increased among patients with all tumor sizes, and there was wide variation in use of this treatment among hospitals, according to a study in the August 17 issue of JAMA.
"More than 40,000 individuals in the United States receive a thyroid cancer diagnosis each year, and the overwhelming majority of cases are well-differentiated thyroid cancer. Standard treatment for well-differentiated thyroid cancer is thyroidectomy. To ensure full eradication of remnant thyroid tissue and to treat residual disease in patients with visible, inoperable, iodine-avid metastases, radioactive iodine is often administered after total thyroidectomy," according to background information in the article. Previous studies have shown improved survival and reduced tumor recurrence when advanced-stage, well-differentiated thyroid cancer is treated with radioactive iodine. "In contrast, for very low-risk disease, in which prognosis is typically excellent, treatment with radioactive iodine is of uncertain benefit."
Megan R. Haymart, M.D., of the University of Michigan, Ann Arbor, Mich., and colleagues conducted a study to determine 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 analysis included 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 researchers found that during this time period there was 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. In 1990, 1,373 (40.4 percent) of 3,397 patients received radioactive iodine whereas in 2008, 11,539 (56.0 percent) of 20,620 received radioactive iodine. Analysis indicated that younger age and absence of comorbidity were associated with a small but significantly greater likelihood of receiving radioactive iodine after total thyroidectomy. Also, female sex, African American race, and absence of private/government insurance were associated with significantly less likelihood of receiving radioactive iodine.
The researchers also found that there was 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. When hospital case volume was analyzed, there was an increased likelihood of radioactive iodine use as the volume of thyroid cancer cases treated at a hospital increased.
"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," the authors write. "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 researchers 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 overtreatment and undertreatment of disease, indications for radioactive iodine should be clearly defined and disease severity should become the primary driver of radioactive iodine use."
Editorial: The Hazards of Evidence-Based Medicine -- Assessing Variations in Care
Edward H. Livingston, M.D., of the University of Texas Southwestern Medical Center, Dallas, and Robert A. McNutt, M.D., of the Rush University School of Medicine, Chicago, (Drs. Livingston and McNutt are also Contributing Editors, JAMA), write in an accompanying editorial that when there is variability in care, as indicated in this study, it may be difficult to conclude that the care (in this case, administration of radioactive iodine) was appropriate or not without additional information.
"In some cases, evaluating intermediate outcomes such as variation in care or adherence to treatment guidelines without linking processes of care to meaningful clinical outcomes may be uninformative or, worse, misleading. The link between processes of care and outcomes must be convincingly demonstrated for proxy measures to be used in assessing quality."
"Ultimately, treatment decisions are made by patients, not practitioners and not policy makers. Patients rely on physicians and other health care professionals to deliver the most amount of information possible about treatment risks and benefits. Patients then can consider these issues in the context of their own individual preferences. Policy makers should not interfere with this process unless the evidence they use to mandate care is substantial. Because of uncertainly in the integrity of most administrative databases and registries and the inherent limitation in the amount of information they contain about patient care, policy should only rarely be made based on findings from these sources."
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