Is Thyroid Cancer Over-Diagnosed?
Rates of thyroid cancer diagnosis have tripled in the past 3 decades, but death rates from the disease have remained the same. The data suggest that thyroid cancer is overdiagnosed and overtreated in people with small tumors that might not cause symptoms or otherwise affect their health, according to a study in the April issue of JAMA Otolaryngology–Head & Neck Surgery.
“Patients should know that we are finding thyroid cancers that may never cause them any harm,” said lead author Louise Davies, MD, who is Associate Professor of Surgery at Geisel School of Medicine, Hanover, NH, and at The Dartmouth Institute for Health Policy & Clinical Practice, Lebanon, NH, and is on faculty with the VA Outcomes Group, White River Junction, VT. Many people who die from other causes are found to have thyroid cancer, “never knowing they had it while they were alive,” Dr. Davies said, adding that women “are more likely to be affected by incidental detection than men.”
“This study shows that we are diagnosing more and more tiny thyroid cancers,” commented R. Michael Tuttle, MD, Professor of Medicine and an endocrinologist at Memorial Sloan Kettering Cancer Center, New York, NY. “The question is when you find these small papillary thyroid cancers, does treating them do more harm than good?,” said Dr. Tuttle who also chairs the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) panel for Thyroid Carcinoma.
The researchers examined the federal government database known as the Surveillance, Epidemiology, and End Results (SEER) program to identify patients diagnosed with thyroid cancer between 1975 and 2009. During that time, the rate of thyroid cancer tripled—from 4.9 to 14.3 cases per 100,000 people—mostly due to an increase in small papillary thyroid cancer, which rose from 3.4 to 12.5 per 100,000 people. The overall increase in diagnosis was nearly four times greater in women than in men with rates increasing from 6.5 to 21.4 cases per 100,000 women.
Death Rates from Thyroid Cancer Have Not Changed
Despite the increasing rates, the death rate from thyroid cancer has remained stable at 0.5 deaths per 100,000 people. The authors suggested that the increasing rates of thyroid cancer may be due to an increase in the detection of subclinical papillary thyroid cancers, which are unlikely to affect patients’ overall health.
Dr. Davies said “active surveillance, instead of undertaking removal of certain thyroid cancers that meet specific criteria, can be a good option for some patients. It requires open and ongoing dialogue with one's physician, and both parties should be comfortable with this approach.”
“The mortality rate in these small nodules is less than 1%,” commented Dr. Tuttle. “So we are beginning to ask, is cancer even the right thing to call these small nodules, because cancer is such a powerful word. There is huge pressure in the United States to find cancer and take it out.
NCCN Guidelines Recommendations Regarding Biopsying Small Nodules
The National Comprehensive Cancer Network (NCCN) does not recommend biopsy of thyroid nodules that are less than 1 cm, unless the patient has high risk clinical features, in which case nodules smaller than 1 cm may be evaluated depending on clinical concern. However, “It is really hard to tell someone that they have cancer, prove it, and then tell them not to do anything about it. So it is important for clinicians to resist biopsying these small nodules,” Dr. Tuttle said. Another component is patient education, he said.
“I tell patients with small papillary cancers, ‘we are not going to make a decision today about whether we are ever going to need surgery or not, but we are going to say that surgery is not necessary right now and that we have time to monitor with ultrasound,’” Dr. Tuttle explained. “I also tell them, ‘if I am wrong and if you are one of the few patients whose tumor grows in 6 months or a year, we are still going to be able to treat this just fine,’” he said.
Dr. Tuttle added that if a small papillary cancer is diagnosed and surgery is required, the NCCN Guidelines for Thyroid Carcinoma recommend removing the affected lobe instead of performing a total thyroidectomy or using radioactive iodine.
Dr. Tuttle is part of a 4-year, National Cancer Institute-funded study investigating whether there is a molecular signature that indicates a patient is among the 1% of patients with papillary thyroid cancer who may develop progressive disease or clinically significant metastases.