RAI More Likely for Low-Risk Thyroid Cancer in Poor Areas

Nancy A. Melville

October 25, 2013

SAN JUAN, Puerto Rico ― The routine use of postoperative radioactive iodine (RAI) ablation for the treatment of low-risk papillary thyroid cancer ― a practice discouraged by endocrinology practice guidelines ― is much more likely to occur in areas of the United States where access to healthcare is poor, according to research presented at the 2013 Annual Meeting of the American Thyroid Association (ATA).

"Counties that are significantly more likely to use radioactive therapy for very-low-risk papillary thyroid cancer patients are those where more of the population is uninsured and where more of the residents are poor, have only a high school education, do not speak English, and are unemployed," said Luc G. T. Morris, MD, a surgical oncologist with the Memorial Sloan-Kettering Cancer Center, in New York City, who presented the new findings.

With the increased use of neck ultrasonography, the rate of thyroid-cancer diagnosis has soared in the United States since the 1970s, with the vast majority of new cases representing tumors of 2 cm or smaller that were previously harder to detect.

A particularly alarming result of this trend has been the often-unnecessary treatment of these smaller cancers with RAI, Dr. Morris explained.

"What we're seeing over time is the spectrum of thyroid cancer is shifting towards the milder end of the spectrum, but at the same time, we are treating it more aggressively, and as many as half of patients undergoing surgery will receive radioactive iodine,” he said.

But the most recent guidelines from the ATA make clear that use of RAI in intrathyroidal cancers of 1 cm or less should be discouraged ( Thyroid. 2009;19:674-675), Dr. Morris noted.

"The guidelines tell us there is no decreased risk of death or of recurrence with the use of radioactive iodine. The evidence is clear that the harms outweigh the benefits." The risks associated with RAI include the possibility of a secondary malignancy, dysphagia, and salivary dysfunction, he noted.

A Third of Papillary Thyroid Cancer Patients Got RAI

To investigate any correlation between healthcare access and patterns of RAI use, Dr. Morris and his colleagues analyzed data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) cancer registry from 337 US counties from 1983 to 2009, which included 13,401 cases of very-low-risk (defined as ≤1 cm) classical papillary thyroid cancer for patients who underwent total thyroidectomy.

Eight socioeconomic factors were used in determining county-level access to healthcare, including the percentage of residents who were uninsured, poor, unemployed, employed in white-collar jobs, non-English speaking, high-school educated, or college educated. Mean family income was also taken into account.

They found that around a third (32.9%) of patients with very-low-risk papillary thyroid cancer received postoperative RAI, a figure that was stable between 1990 and 2009 and ranged from 30% to 36%.

In ranking the counties by socioeconomic factors, use of RAI was more common in the lowest decile compared with the highest (42.0% vs 29.8%, P = .04).

The combined socioeconomic markers of access to healthcare explained 17% of county-by-county variation in the use of RAI for papillary thyroid cancer, the researchers determined.

Although counties with the lowest markers of access had the highest RAI usage rates, "counties least likely to use radioactive iodine for low-risk patients tended to be the ones with the highest number of college-educated residents and white-collar–employed residents and [those with the] highest incomes,” Dr. Morris said.

He noted that the findings add to mounting evidence regarding wide disparities in the use of RAI for this indication. He cited a striking study of 397 hospitals across the United States, published in 2011, showing that the chances of RAI in a young woman with a stage 1 microcarcinoma ― "arguably the lowest-risk patient you can imagine" ― ranged from 0 all the way to 100%, depending on the hospital ( JAMA. 2011;306:721-728).

Is Practice Pattern a Result of Overcaution?

Dr. Morris speculated about possible explanations behind his new findings.

"It may be poorer access to experienced surgical or nonsurgical specialists in those counties with poorer access to care; it may just be that there is a larger denominator in the higher-access counties ― the more affluent, well-educated residents…are having more thyroid nodules found, biopsied, and resected, but perhaps at the end of the line, when it comes to use of radioactive iodine, perhaps those physicians are less likely to use it."

But responding from the audience, John Andrew Ridge, MD, MPH, chief of head and neck surgery at the Fox Chase Cancer Center's department of surgical oncology, in Philadelphia, Pennsylvania, proposed a different theory.

"Physicians may be inclined to deliver what they consider more complete treatment in settings where they fear patients may not return for additional care," said Dr. Ridge, who is also cochair of the National Cancer Institute's Head and Neck Cancer Steering Committee.

"I submit that that is a possible reason for this kind of care pattern that warrants considering."

Thus, in such circumstances, the use of RAI on low-risk patients may have little to do with a lack of awareness and more to do with an increased need to err on the side of caution, Dr. Ridge told Medscape Medical News.

"Guidelines are simply that ― they're guidelines, and we need to be aware of reasons that people depart from them. If you get into an environment where the health system is thin or the patients can't come back or won't come back, then the concern is the recurrence won't be detected in a timely way, and there are often deviations from the guidelines in underserved environments."

Dr. Morris agreed that this is possible. "It could that a physician indeed feels that the patient is less reliable; likewise, it may be a feeling that that the surgeon is less reliable," he observed.

"In general, the Dartmouth Atlas of Health Care has shown us that sicker patients with poorer access to care in general are accustomed to getting more treatment, and certainly I think that is a very valid explanation.

"The question of whether that has validity when there is harm to the treatment and probably very little benefit is an interesting point," he concluded.

The authors and Dr. Ridge have disclosed no relevant financial relationships.

2013 Annual Meeting of the American Thyroid Association. Abstract 98, presented October 18, 2013.

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