As many as 40% of thyroid nodule surgeries involve nodules that are asymptomatic. These nodules are often detected by chance during imaging for other purposes, new research shows. Cancer was found only in 46% of these cases.
“The results of this study suggest that detection of thyroid nodules in asymptomatic patients is still responsible for a substantial number of thyroid surgeries, rather than an increase in the true incidence of thyroid cancer,” say the authors.
The study was published on July 14 in JAMA Otolaryngology–Head and Neck Surgery.
Because these asymptomatic nodules often represent small cancers that may be better managed with active surveillance than with surgery, the findings emphasize the need for awareness so as to prevent overtreatment of those cases, say the authors of a commentary published with the study.
“Despite a lack of symptoms, patients are found to have thyroid pathology, most often thyroid nodules, which begins a process that often ends with surgery and the diagnosis thyroid cancer,” write the editorialists, Tylor Drake, MD, and Emiro Caicedo-Granados, MD, of the Department of Medicine, University of Minneapolis, Minnesota.
“This aggressive evaluation and treatment cascade of asymptomatic patients is likely contributing to the overdiagnosis and overtreatment of thyroid cancer,” they write.
Study Details
For their study, first author Mirabelle Sajisevi, MD, of the Department of Surgery, Division of Otolaryngology, University of Vermont Medical Center, in Burlington, Vermont, and colleagues evaluated data from 1328 patients who had undergone thyroid-directed surgery at 16 centers in four countries, which included 12 centers in the US and one center each in Denmark, South Africa, and Canada.
At each center, these patients represented the first 100 patients or the largest number of patients who received thyroid surgery at the center in 2019.
Their mean age was 52 years, and 75% were women.
Among them, 34% (448) of patients had experienced thyroid-related symptoms, while 41% (542) were asymptomatic.
The remaining 21% of patients either underwent the surgery for endocrine conditions such as hyperthyroidism or were under surveillance and the original mode of detection was unknown.
Cancer Found in 46% of Patients
Overall, cancer was found among 46% (613) of the patients. Of those, only 30% (83) of cases had been symptomatic; 51% (310) of patients did not have thyroid-relevant symptoms.
Most cancers among asymptomatic patients were smaller than those in the symptomatic group (mean, 2.1 cm vs 3.2 cm).
Among asymptomatic patients, 60% of the tumors were less than 2 cm, while 39% were larger than 2 cm.
While the detection of larger nodules in asymptomatic patients is notable, the rate is consistent with historical data, the authors report.
“These findings are consistent with population-based studies showing that most newly detected thyroid cancers are the smaller cancers, although larger cancers are also found in people without symptoms,” they write.
As expected, the percentage of tumors larger than 4 cm was much lower in the asymptomatic group (9%) than in the symptomatic group (29%).
A further evaluation into the mode of detection of the nodules showed that for asymptomatic nodules, 6% were detected as a result of diagnostic cascade, 20% were radiologic or incidental findings, 1% were detected at patient-requested screening, and 13% were detected on clinician screening examination.
Of the incidental findings, the leading sources of detection were chest CT (31%; 82 cases) and MRI of the neck (16%; 42 cases).
A geographic evaluation showed that South Africa and Denmark had the highest rates of nodules discovered in symptomatic patients, with rates of 79% and 54%, respectively, compared with just about 30% in the US and 30% in Canada.
The authors speculate that strict indications for thyroidectomy in Denmark and limited resources in South Africa may explain the lower rates of surgeries for small asymptomatic nodules in those countries.
Detections Rise, but Not Mortality Rates
An approximately threefold increase in the detection in the incidence of thyroid cancer in the US has been linked primarily to the detection of small, subclinical cancers. This increase has not been associated with improved mortality rates, the authors note.
The current study’s cancer detection rate of 46% represents an increase over the 34% reported in a previous study that also evaluated the mode of detection, which could be a favorable sign, “possibly reflecting the increasing use of molecular testing in the past decade to select nodules for surgery that are likely to be malignant,” the authors write.
To further reduce unnecessary surgeries, they urge that “educational outreach and studies evaluating the safety and usefulness of a monitoring approach for patients with low-risk thyroid nodules may help decrease the risks of overtreatment while identifying those patients with nodules that would benefit from early intervention.”
In their commentary, Drake and Caicedo-Granados note that the average size of nodules in the study was not as small as commonly reported with asymptomatic nodules ― possibly another sign that fewer smaller nodules are being surgically treated.
“Interestingly, both [symptomatic and asymptomatic] groups had tumors with a mean size of more than 2 cm,” they note.
“Small papillary thyroid carcinomas (PTC) have historically been treated surgically, but more recent studies have shown that a watchful waiting approach to biopsy-proven PTC less than 2 cm can be an appropriate treatment strategy.
“This nonsurgical approach to small PTCs is likely contributing to the larger tumor sizes seen in this study of patients who underwent thyroid surgery,” they say.
Efforts to reduce interventions for low-risk thyroid nodules, when appropriate, have been promoted through programs including the Choosing Wisely campaign in the US, as well as through guidelines.
The authors of the commentary agree that “future efforts are required to shift toward a less aggressive [evaluation and treatment] process, including preventing inappropriate evaluation with screening thyroid ultrasonography and increased implementation of active surveillance protocols of small PTCs, to avoid unnecessary and inappropriate thyroid surgery.”
The original article lists the study authors’ relevant financial relationships. The authors of the commentary have disclosed no such relationships.
JAMA Otolaryngol Head Neck Surg. Published July 14, 2022. Abstract, Commentary
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