Radioiodine being overused in thyroid cancer: Study

By Dr. Ananya Mandal, MDAug 17 2011

According to the latest research the use of radioactive iodine to treat thyroid cancer increased 40 percent from 1990 to 2008 even though the risks may outweigh the benefits for some patients, particularly those with early-stage tumors.

The new study in the Journal of the American Medical Association shows that nearly 56 percent of thyroid cancer patients in 2008 were treated with radioactive iodine, which is used after the thyroid is removed to treat residual cancer, compared with 40 percent in 1990. Determining who gets the treatment doesn’t always depend on how severe the cancer is, researchers found.

“Thyroid cancer is the 10th most common cancer in the U.S. with more than 40,000 people diagnosed with the disease each year, according to the study authors. Medical guidelines suggest doctors reserve radioactive iodine for the most aggressive thyroid cancers yet left the option open to physicians for use in patients with less serious tumors”, said Megan Haymart, the study’s lead author.

Haymart, an assistant professor of internal medicine at the University of Michigan in Ann Arbor explained, “There are some risks for this, so this rise in use of radioactive iodine coupled with the fact that it’s not being tailored to disease severity is somewhat worrisome…There need to be more studies on which patients need radioactive iodine. Patients with small, low-risk tumors often do fine with just thyroid removal and no radioactive iodine, which can cause secondary cancers and damage to tissues near the thyroid including salivary glands and tear ducts.” Haymart added, “Patients must also stay away from young children for a week and avoid becoming pregnant for up to a year after treatment.”

Researchers in the study looked at data from 189,219 people diagnosed with thyroid cancer at 981 hospitals between 1990 and 2008 in the National Cancer Database, which captures about 85 percent of the thyroid cancers diagnosed in the U.S. They found an increase in radioactive iodine use across all tumor types from the least to the most severe. “For some patients, radioactive iodine is a very important part of treatment, but for others, the risks may outweigh the benefit,” she said in a statement.

The study revealed that those most likely to receive radioactive iodine were younger, male, had private or government insurance and those without other health conditions. Those with the most aggressive cancer were more likely in the study to receive radioactive iodine than those with stage I. While, those with stages II and III were just as likely as those with stage IV cancer to receive the treatment, the study found. Patients were also more likely to be given radioactive iodine if they were at hospitals that often treat thyroid cancers, the researchers said.

“Unfortunately many of the treatment centers tend to lump all thyroid cancers together and don’t really individualize their treatment and many patients have an expectation that they need more treatment when in fact they do not,” said Irwin Klein, director of the Thyroid Unit at North Shore University Hospital in Manhasset, New York. “We’re detecting smaller and smaller thyroid tumors,” said Klein, who offered his opinion on the research. “While most people agree that surgery is appropriate to remove those tumors, the data out there suggests that these patients don’t need to be treated the way that larger, bulkier tumors are treated with radioactive iodine.”

“There are a lot of patients who are receiving iodine for what is considered low-risk tumors,” said Dr. David J Sher, a cancer expert at Rush University Medical Center in Chicago. “These patients generally have a superb prognosis without radioactive iodine,” he said.

Despite the grim picture, an editorial in the journal warns that relying on databases can sometimes be misleading. Doctors and patients may have had good reasons to choose iodine treatment even with low-risk tumors, and those wouldn't necessarily be clear from the database. Still, Sher said, “We know patients are getting over-treated, we know patients are getting under-treated, now we have to find out why.”