Rise in thyroid cancer diagnoses is challenged by Mayo researchers

Overdiagnosis of thyroid cancer in the United States could be causing thousands of patients to receive costly and unnecessary procedures that won't increase the quality or length of their lives.

The findings, published Tuesday by doctors at the Mayo Clinic, have prompted the researchers to recommend a new diagnostic term that could spare people with small throat tumors from surgery, medication and radiation that they might not need.

The rapid expansion of high-tech imaging has identified thyroid lesions that once went undetected — and fueled a tripling in the diagnosis of thyroid cancer in the United States over the past 30 years. But the increases in diagnoses and treatment haven't changed the death rate from thyroid cancer, leading the researchers to question whether the effort is wasted on patients who could lead healthy lives without medical intervention.

"This is exposing patients to unnecessary and harmful treatments that are inconsistent with their prognosis," said Dr. Juan P. Brito, a Mayo endocrinologist in Rochester.

In a British Medical Journal article released Tuesday, Brito and colleagues argued that people with common "papillary" thyroid tumors smaller than 20 millimeters and no family history of thyroid cancer should be diagnosed with a new term — "micropapillary lesions of indolent course," or microPLICs.

Giving these lesions a label other than cancer would lead more doctors and patients to simply wait to see if they grow or cause symptoms. Absent those problems, patients could avoid treatments that can include surgical removal of some or all of the thyroid gland and the consumption of radioactive iodine that targets and kills thyroid cells, including cancer cells.

Many patients who undergo surgery need lifelong medication to compensate for the loss of the thyroid, a butterfly-shaped gland in the throat that regulates the release of hormones that control growth, energy, mood, body temperature and other functions.

While thyroid cancer isn't as common as cancers of the breast, lung or colon, it is the third-fastest-growing cancer in terms of the rate of diagnosis. The problem is similar to the overdiagnosis of prostate cancer based on PSA blood tests that can be misleading.

Autopsies have found patients who died of heart disease or other ailments and had tumors in their thyroid glands or prostates that never caused problems.

International variations in rates of thyroid cancer suggest that the disease is overdiagnosed in the United States. There is no other ready explanation why the rate would have increased in the United States from about 6 cases per 100,000 people in 1985 to 11 cases per 100,000 in 2002, when the rates stagnated in Norway, Sweden and Japan.

A July study by New York cancer experts also found that diagnostic rates in the United States were higher for people with wealth and health insurance. A real increase in cancer would have likely transcended these economic demographics.

Doctors need to use more restraint in their use and interpretation of ultrasounds and high-tech imaging scans, and learn to differentiate harmful lesions from potentially harmless ones, said Dr. Otis Brawley, chief medical officer of the American Cancer Society, a national advocacy group.

Apart from waiting and watching, doctors have alternatives such as surgically removing lesions without prescribing the radioiodine treatment, or using laser ablation to shrink them.

Susan Evans of St. Paul, who underwent treatment last year to remove a lesion in her thyroid gland, said the overtreatment problem might, in part, reflect doctors not talking enough with one another about options before passing along test results or recommendations.

More coordination between the ear, nose and throat specialists, endocrinologists and other physicians might produce a more cautious treatment plan, she said.

"If they were to work a little more hand in hand … in these cases, I think some people would be able to sit it out a little more," Evans said.

Removing the cancer label might encourage more conservative treatments, but doctors would still need to be vigilant of small tumors, said Dr. Anders Carlson, an endocrinologist with HealthPartners in St. Paul.