Thyroid Cancer: Epidemic or Overdiagnosis?

with Michael Tuttle, MD

This year, more than 60,000 people in the US will learn they have thyroid cancer, according to estimates from the American Cancer Society.1

A butterfly-shaped gland located at the bottom of your neck is responsible for releasing key hormones that control metabolism and other essential body functions, such as breathing, heart rate, and body weight.

Often thyroid nodules under 1 cm can be watched rather than removed.Most small thyroid nodules are benign, meaning you do not need to have your thyroid removed. In fact, experts now believe that unless they grow or cause a problem, you are better off waiting. Photo: Thomas Schmidt @ iStock

While hearing that you may have cancer is always worrisome and sobering, many experts now say that not everyone with a thyroid nodule needs immediate treatment, or any treatment at all—if the tumor is very small when first detected—as most are.

Traditional Thinking Requires New Thinking

Attitudes are changing about how to treat these smallest thyroid cancers, according to a Mayo Clinic expert speaking at the opening session of the American Thyroid Association's annual meeting in Denver.

"The pendulum is swinging," says Ian D. Hay, MD, PhD, the Dr. Richard F. Emslander professor of endocrinology and nutrition research at Mayo Clinic, Rochester.

That's because more than 80% of tumors found are papillary thyroid cancers, he says. And many are tiny, measuring no more than a half inch (about 1 centimeter), and stay that way.

In years past, traditional thinking was to treat all thyroid cancers, often by removing the gland, Dr. Hay says. Now, less intensive treatments, far short of removing the entire gland, are becoming the trend. In some patients, no immediate treatment is recommended, an approach called ''active surveillance with curative intent.'' This approach, a kind of ''watchful waiting,'' means your doctor may suggest monitoring the tumor to see if it becomes larger, and only treat it if it does, Dr. Hay says.

Could Finding So Many Nodules Mean Cancer for Everyone?

Over the past few years, experts have reported an ''epidemic'' of thyroid cancer. In the U.S., 37,000 thyroid cancers were diagnosed in 2009, but by 2014, about 63,000 were.2

However, as the number of new cases of thyroid cancers climbed, the death rate from the cancers remained stable, as other researchers reported.

That led to several published reports in medical journals saying that the rise in cases is actually due to more frequent detection of the tumors, including very tiny cancers that went unnoticed before advances in detection methods occurred, Dr. Hay says. 3

Left alone, or treated less aggressively, many of these tumors will cause no problems, says Dr. Hay, who cited evidence from his own Mayo Clinic data base and other research. "At Mayo, we have also seen, since 1994, a tripling of the numbers of patients diagnosed with [the tiny cancers]," he says.

In his talk, Dr. Hay also reported on more than 1,300 patients with small cancers, treated at Mayo from 1935 to 2014 who underwent a variety of treatments.  "After an average follow up of more than 15 years, only 4 patients, or .3%, had died from thyroid cancer, while almost a third of the [study group] died of other causes."

The patients had a normal life expectancy, he says, and the extent of the initial surgery did not affect whether the cancer came back. The more aggressive the surgery, he did find, the higher the risk of nerve damage and damage to the parathyroid glands, which are located behind the thyroid and help regulate calcium.

In 2016, the American Thyroid Association issued a statement saying that some thyroid cancers will never result in symptoms or death and only rarely enlarge or spread. 4 It issued new guidelines on thyroid cancer in 2015, saying that fine needle aspiration (a technique used to help diagnose cancer when thyroid nodules are found) is not required for growths less than 1 centimeter (about .40 inch) that appear to be confined to the gland. Thyroid nodules are lumps or growths found on the gland. They can be biopsied but are usually not cancerous.5

Relax—Little Tumors Mean Little Need for Treatment

Not all experts agree that less is better, says Michael Tuttle, MD, clinical director of the endocrinology service at Memorial Sloan-Kettering Cancer Center, NY. He commented on Dr. Hay's presentation. However, he says that both physicians and consumers ''are starting to recognize that we can find little cancers that don't need to be treated immediately." 6

The concept of active surveillance, he says, is similar to that adopted for some prostate cancers. Dr. Tuttle is studying the approach now in 300 very low-risk thyroid cancer patients at Memorial Sloan-Kettering. Only a few years ago, he says, people were questioning the concept. "Now, most of the questions I get [after lecturing on the topic] is 'How do you do that?' or "Which patients are appropriate?'''

For anyone found to have a thyroid nodule, Dr. Tuttle offers this insight: "Thyroid nodules are really, really common. They are almost always benign.''

"If someone wants to biopsy a nodule less than a centimeter, you should either question if that is needed or seek a second opinion.'' He says a few do need to be biopsied, such as nodules lying close to other vital structures. But a doctor should explain why he wants to biopsy a very small nodule, he says.


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