Radioactive iodine usage after thyroid surgery for different stages of thyroid cancer is up, but there are few guidelines outlining proper dosages and usage. So what is it and what do patients and health providers need to know?

First, your thyroid gland absorbs nearly all of the iodine in your blood. When a large enough dose of radioactive iodine (RAI), also known as I-131, is taken into the body, it can destroy the thyroid gland and any other thyroid cells (including cancer cells) that take up iodine, with little effect on the rest of your body.

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 new study released this week which states:

“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. In contrast, for very low-risk disease, in which prognosis is typically excellent, treatment with radioactive iodine is of uncertain benefit.”

A study was conducted 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.

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.

The report continues:

“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.”

Radioactive iodine therapy has been shown to improve the survival rate of patients with papillary or follicular thyroid cancer (differentiated thyroid cancer) that has spread to the neck or other body parts, and this treatment is now standard practice in such cases. But the benefits of RAI therapy are less clear for patients with small cancers of the thyroid gland that do not seem to have spread, which can often be removed completely with surgery. Radioactive iodine therapy cannot be used to treat anaplastic (undifferentiated) and medullary thyroid carcinomas because these types of cancer do not take up iodine.

The analysis concludes:

“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.”

Written by Sy Kraft