No Symptoms, No Thyroid Screening, Says USPSTF

Nick Mulcahy

May 09, 2017

The United States Preventive Services Task Force (USPSTF) recommends against screening for thyroid cancer in asymptomatic adults and thus discourages the practice, according to a new final statement.

"While there is very little evidence of the benefits of screening for thyroid cancer, there is considerable evidence of the serious harms of treatment, such as damage to the nerves that control speaking and breathing," said task force member Karina W. Davison, PhD, of Columbia University Medical Center in New York City, in a statement.

The USPSTF's new recommendation, which is similar in conclusion to its last issuance on the subject in 1996, is published online in JAMA and on the USPSTF Web site. A draft recommendation had been available for public comment from November 22 to December 26, 2016, as reported by Medscape Medical News.

The new recommendation does not apply to patients with symptoms of thyroid cancer. Symptoms include those of the throat, such as hoarseness, pain, and difficulty swallowing, as well as those of the neck, such as lumps, swelling, and asymmetry.

The USPSTF said it found "inadequate direct evidence" to determine whether screening for thyroid cancer in asymptomatic persons using neck palpation or ultrasound improves health outcomes.

The authors issued a grade D recommendation, the lowest possible score, which means "there is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits."

The USPSTF also highlights the facts that, although the incidence of thyroid cancer detection has increased by 4.5% per year during the past 10 years, there has been no corresponding change in the mortality rate and that the 5-year survival rate for thyroid cancer overall is 98.1%.

"The rationale for the recommendation against screening is compelling," writes Anne Cappola, MD, an endocrinologist at the University of Pennsylvania, in an accompanying JAMA editorial. Her editorial is one of four published in different JAMA publications. She agreed that the harms outweigh any benefits of screening.

 
The rationale for the recommendation against screening is compelling. Dr Anne Cappola
 

The slogan "check your neck" (ie, undergo screening) is "well

The slogan "check your neck" (ie, undergo screening) is "well intentioned," but the new USPSTF recommendation "should discourage clinicians from screening for thyroid cancer with neck palpation, ultrasonography, or other techniques," say Louise Davies, MD, an otolaryngologist at the Geisel School of Medicine at Dartmouth in Hanover, New Hampshire, and Luc Morris, MD, a surgeon at Memorial Sloan Kettering Cancer Center in New York City, in an editorial published online in JAMA Otolaryngology – Head and Neck Surgery.

However, they too observe that thyroid cancer incidence in the United States has been rising. Plus they say that "approximately 67% of adults have thyroid nodules found on ultrasonographic examination."

"So why not screen for thyroid cancer?" the pair ask. The answer is that screening is only beneficial if it makes death from thyroid cancer less likely or improves quality of life.

The USPSTF found that neither has occurred.

Instead, the USPSTF found that for cases of low-risk asymptomatic papillary thyroid cancer (the type most commonly detected on imaging), there is no evidence that treatment of asymptomatic patients was associated with better outcomes than treatment of symptomatic patients. In other words, early detection did not matter.

Dr Davies and Dr Morris also point out that studies of thyroid cancer patients managed with active surveillance, which were cited by the USPSTF, indicate that more than 90% of small papillary thyroid cancers do not grow under observation, even after many years.

Furthermore, say this pair, epidemiologic data "from around the world" demonstrate that finding more cases of thyroid cancer has not made death from the disease less likely. This is true in South Korea, where a government program provides thyroid cancer screening, as well as in the United States, where the detection is frequently due to incidental findings related to other imaging.

Dr Davies and Dr Morris also point out that only about 1600 adults in the United States die of thyroid cancer annually, but an estimated 250 million adults have thyroid nodules.

This means that if population-wide screening were to occur, a huge group of individuals, after having their nodules detected, might undergo diagnostic tests, invasive procedures, and have related anxiety. And even when thyroid cancers are detected, there is the "very likely possibility" that they would be indolent, the pair says.

With regard to harms, the USPSTF reports in its systematic review of evidence (JAMA. 2017;317:1888-1903), which included 36 studies with 43,295 patients, the rate of surgical harm was 2.12 to 5.93 for cases of permanent hypoparathyroidism per 100 thyroidectomies and 0.99 to 2.13 cases of recurrent laryngeal nerve palsy per 100 operations.

Why Has the Incidence Rate Increased in the US?

The new USPSTF recommendation "should have been an easy decision," given the historical context, says H. Gilbert Welch, MD, MPH, from the Geisel School of Medicine at Dartmouth, writing in a separate editorial published online in JAMA Internal Medicine.

Dr Welch chronicles various study findings from the past that reveal a "high prevalence/rare death mismatch." For instance, in Finland, where thyroid cancer–related death is low, a 1985 study found that 36% of 101 consecutive autopsies revealed papillary thyroid cancer, the majority of which were "very small" (Cancer.1985;56:531-538).

Dr Welch says that this, in theory, is "a bottomless reservoir of undetected thyroid cancer."

However, until the mid-1990s, there was no epidemiologic evidence in the United States that medical interventions were "tapping this reservoir," because incidence rates were steady.

So what happened to cause the increase in thyroid cancer? Dr Welch says that some of the increase was the result of "incidental" findings and resulted from an increase in the use of chest and neck CT and carotid ultrasonography.

But some detection was "apparently purposeful," resulting from "systematic physical examination of the neck followed by ultrasonographic evaluation of detected nodules," he says. "That sounds like screening," Dr Welch adds.

He also reminds readers of the Light of Life Foundation's public service announcements from about 10 years ago in the United States, which encouraged people to have their physicians "check your neck" and described thyroid cancer as "the fastest growing cancer in the US." The corporate sponsors of that public campaign included Sanofi Genzyme, which markets an adjunctive pharmacologic agent (Thyrogen) that is used in conjunction with thyroid radiation therapy, he points out.

Dr Welch concludes that he is grateful for the integrity of the USPSTF and their ability to be independent of professional and financial interests.

What About the Increase in Mortality?

Striking a different note, the University of Pennsylvania's Dr Cappola believes that "the conversation about screening for thyroid carcinoma should not stop." She points to recent SEER data that indicate an increase in thyroid cancer incidence-based mortality of 1.1% per year from 1994 to 2013.

 
The conversation about screening for thyroid carcinoma should not stop. Dr Anne Cappola
 

"Both the incidence of advanced-stage papillary thyroid carcinoma and mortality among these individuals increased over time. These data would not be explained simply by overdiagnosis," she says about the SEER findings.

However, the increase in thyroid cancer incidence-based mortality is based on very small numbers in the SEER database, as reported by Medscape Medical News in March.

At that time, Dartmouth's Dr Davies observed that there were about 56 thyroid cancer-related deaths per year on average, which she said suggested the possibility of alternative explanations for the increase in percentages during the study period.

Dr Davies also indicated that the change in mortality was only significant for people with a papillary thyroid cancer that had spread outside the neck at the time of presentation, which represents <5% of all cases. "There was no significant change in mortality rates for people presenting at earlier stages of disease," Dr Davies said.

However, Julie Ann Sosa, MD, a surgeon of Duke University in Durham, North Carolina, and two colleagues believe that the recent SEER data, as well as some other relatively new findings, suggest that "we pause and recalibrate" regarding thyroid cancer screening.

Writing in an editorial published online in JAMA Surgery, this team says that clinicians need to be reminded of the value of the neck examination.

Dr Sosa and colleagues fear that the recommendation against neck palpation as a screening tool for thyroid cancer could be "overinterpreted" by some clinicians to "exclude examination of the neck as an essential component of routine clinical care and fastidious physical examination."

They add: "Palpation of the thyroid gland itself, along with the central and lateral compartments of the anterior neck, can provide important information about thyroid nodules, goiter, lymphadenopathy, bruits, thrills, and other findings that could have critical bearing on a litany of benign and malignant conditions that extend far beyond the thyroid."

Therefore, the USPSTF statement should assert that neck palpation should remain a necessary pillar of a good physical examination, they argue.

This research was funded by the Agency for Healthcare Research and Quality under a contract to support the USPSTF. Dr Sosa is a member of the data monitoring committee of the Medullary Thyroid Cancer Consortium Registry, which is supported by NovoNordisk, GlaxoSmithKline, AstraZeneca, and Eli Lilly. The other authors and editorialists have disclosed no relevant financial relationships.

JAMA. Published online May 9, 2017. Full text

JAMA Otolaryngol. Published online May 9, 2017. Editorial

JAMA Surg. Published online May 9, 2017. Editorial

Follow Medscape senior journalist Nick Mulcahy on Twitter: @MulcahyNick

For more from Medscape Oncology, follow us on Twitter: @MedscapeOnc

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