High-tech imaging contributing to overdiagnosis of low-risk thyroid cancers

An increasing gap between the incidence of thyroid cancer and deaths from the disease suggests that low-risk cancers are being overdiagnosed and overtreated, a study from the Mayo Clinic Center for the Science of Health Care Delivery finds. The study appears in the current issue of the British Medical Journal.

"High tech imaging technologies such as ultrasound, CT and MRI can detect very small thyroid nodules many of which are slow growing papillary thyroid cancers, says the study's lead author Juan Pablo Brito, M.B.B.S. an endocrine fellow and health care delivery scholar at Mayo Clinic. "This is exposing patients to unnecessary and harmful treatments that are inconsistent with their prognosis."

Dr. Brito says the surgical removal of all or part of the thyroid gland is a costly procedure and includes a risk of complications such as low calcium levels and nerve injury. Surgical removal procedures in the United States have tripled in the past 30 years - from 3.6 per 100,000 people in 1973 to 11.6 per 100,000 people in 2009.

"Uncertainty about the benefits and harms of immediate treatment for low-risk papillary thyroid cancer should spur clinicians to engage patients in shared decision-making to ensure treatment is consistent with the research evidence and patient goals," Dr. Brito says.

To help provide context for patients, Dr. Brito recommends the development of a new term that connotes a favorable prognosis for low-risk thyroid cancers, such as microPapillary Lesions of Indolent Course (microPLIC). A new term would make it easier for clinicians to offer patients the choice of active surveillance instead of immediate and often intensive treatment. He also calls for research to identify the appropriate care for these patients.

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Co-authors include John Morris, M.D., and Victor Montori, M.D., both of Mayo Clinic.

For patients with low-risk differentiated thyroid cancer, there's no hurry to use radioactive iodine after surgery, researchers reported.

The timing of radioiodine remnant ablation appeared to have no effect on outcomes in a retrospective case series, according to Stylianos Tsagarakis, MD, PhD, and colleagues at Evangelismos Hospital in Athens.

A key clinical implication is that the resources and facilities needed to administer radioiodine - if they are limited - can be safely reserved for patients with high-risk disease, Tsagarakis and colleagues reported in Clinical Endocrinology.

For low-risk patients, "urgent administration of (radioiodine remnant ablation) after surgery is not justified," the researchers argued. "Instead, patients with extensive disease must have absolute priority."

Other research has shown that delaying radioiodine remnant ablation in patients with metastatic disease resulted in worse survival, Tsagarakis and colleagues noted.