Thyroid cancer is being over-diagnosed and over-treated, Mayo physicians believe
New imaging technologies have led to the overdiagnosis of thyroid cancer, exposing thousands of people to unnecessary, expensive and potentially risky treatments, according to a study by three physicians at the Mayo Clinic in Rochester.
The problem is particularly acute in the United States. (Huabin’s note: Things aren’t looking good in China either!)
Because of these concerns, Mayo Clinic physicians have suggested a new term to describe those with low-risk thyroid lesions – one that will better convey the message that these lesions pose only a minimal risk to a patient’s health and that will steer patients and physicians away from unnecessary treatments.
Juan Brito, MD, an endocrinologist and one of the authors of the study, said, “We need to rename them, and we need to put them in a different category.”
The study was published in the latest issue of the British Medical Journal (BMJ).
A puzzling phenomenon: a big jump in diagnosis rates
Over the past 30 years, the incidence of thyroid cancer cases has tripled in the United States, from 3.6 cases per 100,000 people in 1973 to 11.6 cases in 2009.
”This makes thyroid cancer one of the fastest growing cancers,” Brito said.
”Incidence rates have been observed to be increasing globally, but they are not evenly distributed,” he added, “for example: Sweden, Japan and China have experienced a gradual increase in the incidence of this particular cancer. “
In addition, almost all new cases of thyroid cancer diagnosed – 90 percent – are so-called small papillary carcinomas, which studies have shown grow very slowly, show no symptoms, and cause little to no death.
This factor most likely explains why the death rate from thyroid cancer has remained constant while diagnoses of new papillary thyroid cancers have skyrocketed.
Key factors behind the increase
Brito and his colleagues, Dr. John Morris and Dr. Victor Montori, explain in their paper that the advent of more papillary cancer diagnoses is due to advances in high-tech imaging techniques, such as the widespread use of ultrasound, CT and magnetic resonance imaging (MRI), which can now detect thyroid nodules as small as 2 mm.
Another factor is reimbursement policies that have encouraged physicians to use these technologies, and in the United States, neck ultrasound has increased by at least 80% since 1980.
Studies have also shown that high-income Americans are relatively more likely to be diagnosed with thyroid cancer than Americans at lower income levels – especially those with health insurance.
”The ease of use and simplicity of these technologies and the drive for misuse of these technologies leads to overdiagnosis,” Brito said.
Unnecessary treatment
In their paper, Brito and colleagues note that overdiagnosis often leads to overtreatment, including unnecessary surgery. In fact, the number of thyroidectomies (surgeries, total or partial thyroidectomies) in the United States rose by 60 percent between 1996 and 2006.
Thyroidectomy is expensive and can have several serious, permanent complications, including damage to the nerves in the larynx. Patients receiving total thyroidectomy or, in some cases, even partial thyroidectomy must take thyroxine replacement therapy for the rest of their lives, a treatment that itself carries health risks.
Radioactive iodine therapy is also increasingly being used to treat low-risk papillary thyroid cancer in the U.S. In 1973, only one in 300 thyroid cancer patients received radioactive iodine therapy. In 2006, that number increased to two out of five. However, radioactive iodine is not recommended in the guidelines for the treatment of thyroid cancer in low-risk patients. These related treatments reduce patients’ quality of life and risk other types of cancer, including leukemia and cancer of the salivary glands.
New terminology needed
Brito and his colleagues acknowledge that there may be some uncertain causes for the rapid rise in thyroid cancer incidence, such as the widespread use of CT scans leading to Russian radiation exposure. But the disparity between incidence and mortality rates and the unevenly high incidence rates across countries suggest that overdiagnosis is behind the soaring incidence of thyroid cancer.
They urge physician-patient participation in decision-making and explain to patients that, in many cases, active surveillance rather than surgical treatment is the most appropriate management of thyroid cancer.
”Patients can be reassured that retreatment if there is evidence that the nodule is exhibiting more aggressive behavior does not cause a delay in treatment.” The authors write in the article.
They also suggest using the term “small papillary lesions” to rename dormant papillary thyroid cancers, which more accurately reflects the minimal health risks they pose to patients.
Most thyroid cancer findings “are not destined to be inevitable or risky for patients,” Brito says, “and by taking away the cancer label, we can reframe the level of management of these diseases and reduce the level of anxiety patients feel about cancer.”
The study, published by Brito and his colleagues, is available on the British Medical Journal’s website.