After thyroid cancer surgery, many patients should be in the position of deciding with their doctors whether to pursue treatment with radioactive iodine to help ease long-term follow-up and offer reassurance that the cancer is gone.

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A new survey by researchers at the University of Michigan Rogel Cancer Center and U-M Institute for Healthcare Policy and Innovation suggests many patients are receiving the treatment when there's no strong indication of benefit — and a majority may feel like they don't really have a choice about it.

"If these patients are empowered to have more say in whether they receive radioactive iodine, one, it might decrease overtreatment and, two, there might be more long-term patient satisfaction with their outcomes and their choices — especially given the burdens that side effects and treatment costs can have," says study senior author Megan Haymart, M.D., a clinician and health services researcher at Michigan Medicine.

The research team's findings appear in the Journal of Clinical Oncology.

Selective use recommended for most patients

Clinical guidelines recommend radioactive iodine for the highest risk patients, and recommend against it for the lowest risk patients. But most patients fall somewhere in the middle, where more cautious, case-by-case decision-making is recommended, Haymart explains. This places the responsibility for whether to pursue the treatment squarely on the shoulders of doctors and their patients.

In the study sample of more than 1,300 of these middle-ground patients, the researchers found that 76% received radioactive iodine and more than half felt they weren't given a choice in the matter.

The patients were identified using the National Cancer Institute Surveillance, Epidemiology, and End Result registries in California and Georgia.

"In our prior work, we found that there's wide variation in the use of radioactive iodine," says Haymart, associate professor of medicine. "And in some instances we found more aggressive use or more intensive use than would be recommended by the guidelines.

"So, we wanted to look specifically at the patients' role in decision making," she says. "In this group of patients for whom selective use is recommended — where there should be a conversation between the patient and physician — did they feel they had a choice as to whether or not they received radioactive iodine? And, unfortunately, the answer is that many did not."

Patients' perception of not having a choice was associated both with greater receipt of the treatment, as well as with lower satisfaction with the decision after the fact, even when adjusting for treatment-related side effects, notes study first author Lauren Wallner, Ph.D., M.P.H., assistant professor of medicine at Michigan Medicine.

Long-term side effects from radioactive iodine treatment can impact patients' quality of life, Haymart says. The biggest issue is damage to patients' salivary glands and tear ducts caused by the radiation. The most commonly reported symptoms include swelling and tenderness of the salivary glands, dry mouth, increased dental cavities and excess tearing due to tear duct obstructions.

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Patients may also briefly experience side effects leading up to and shortly after treatment. They may be placed on low-iodine diets that require cutting down or avoiding foods like dairy, fish and green vegetables. They also have to stop taking thyroid hormone replacement or receive injections of thyrotropin alfa (Thyrogen) prior to radioactive iodine treatment. During the period when they are off thyroid hormone replacement, patients may experience fatigue, mental slowing and weight gain. However, after radioactive iodine treatment is complete, thyroid hormone replacement is restarted and these symptoms typically resolve.

Recommendations for patients and doctors

Why are such a large percentage of patients receiving iodine treatment? Several factors may be at play, Haymart says. One is historical precedent. For many years, radioactive iodine was a standard treatment for most thyroid cancer patients — until outcomes data cautioned that a less aggressive approach might be appropriate for those outside of the highest-risk categories.

SEE ALSO: Reducing Overtreatment in Cancer Patients: When Is Active Surveillance Appropriate?

Another might be a form of confirmation bias: If a doctor gives a treatment and their patient does well, it's easy to believe that the patient did well because of the treatment — even if they might have done equally well without it.

Haymart says it's important for patients to ask their doctors about the potential benefits and risks of radioactive iodine treatment.

"They should ask what the side effects of this treatment are likely to be," she says. "And what the doctor expects to be different in regard to outcome if they receive the treatment or if they decide not to pursue the treatment."

On the physician side, Haymart cautions against a one-size-fits-all approach.

"Doctors should take into account the individual patient, their perspectives and their disease severity, and work with the patients to make these decisions," she says. "Especially in cases such as this where there's not great data on benefit and there are known risks, the patient needs to be fully aware of both the benefits and the risks, and be empowered to have a say in whether treatment occurs."