Use of radioactive iodine for the treatment of well-differentiated thyroid cancer has increased over time in the United States, even among patients who have an excellent prognosis with surgery alone. These results were published in the Journal of the American Medical Association.
The thyroid is a gland in the throat that produces hormones mostly related to metabolic processes in the body. Overall, thyroid cancer is considered to be a highly curable cancer, with 97% of individuals alive at least five years following diagnosis. Nearly 95% of all thyroid cancers are classified as differentiated thyroid cancers; the distinction refers to the type and characteristics of the cancer cells.
Standard treatment for well-differentiated thyroid cancer involves surgical removal of the thyroid. After surgery, some patients benefit from additional treatment with radioactive iodine. Studies have reported that radioactive iodine can improve outcomes among patients with advanced or high-risk thyroid cancer, but there is less evidence that it benefits patients with very low-risk thyroid cancer, who tend to have excellent outcomes with surgery alone. Given the uncertainties, there continues to be debate about which patients should receive radioactive iodine. Treatment is not to be taken lightly because it does carry risks.
To explore trends in the use of radioactive iodine in the United States, researchers collected information from a large cancer database. The database contained information about more than 189,000 patients with well-differentiated thyroid cancer treated between 1990 and 2008.
- Between 1990 and 2008, use of radioactive iodine increased among patients with all tumor sizes. Overall, radioactive iodine was used in 40% of patients in 1990 and 56% of patients in 2008.
- Only 21% of the variability in use of radioactive iodine was explained by patient and tumor characteristics. Much of the variability seemed to be due to which hospital the patient attended.
- Variability in use of radioactive iodine across hospitals was observed for both low-risk patients and high-risk patients. This raises the possibility that some patients are being overtreated while others are being undertreated.
The variability across hospitals in the use of radioactive iodine, and the increasing use even among low-risk patients, raises concerns and highlights the continuing uncertainty about how best to use this treatment. The researchers note “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.”
Reference: Haymark MR, Banerjee M, Stewart AK et al. Use of radioactive iodine for thyroid cancer. Journal of the American Medical Association. 2011; 306:721-728.