Minn. — Low-risk cancers that do not have any symptoms and
presumably will not cause problems in the future are
responsible for the rapid increase in the number of new cases
of thyroid cancer diagnosed over the past decade, according to
a Mayo Clinic study published in the journal Thyroid.
According to the study authors, nearly one-third of these
recent cases were diagnosed when clinicians used high-tech
imaging even when no symptoms of thyroid disease were present.
are spotting more cancers, but they are cancers that are not
likely to cause harm," says the study's lead author, Dr.
Juan Brito Campana, an assistant professor of medicine at Mayo
Clinic. "Their treatment, however, is likely to cause
harm, as most thyroid cancers are treated by surgically
removing all or part of the thyroid gland. This is a risky
procedure that can damage a patient’s vocal cords or leave
them with lifelong calcium deficiencies."
Brito says harm is not limited to physical suffering.
"Treatment can cause financial hardship for patients and
their families and for society as a whole, as millions of
dollars are spent for unnecessary and problematic
surgeries," he says.
to Dr. Brito, the aggregate national cost of these procedures
in the U.S. was $1.6 billion in 2013 and likely will exceed
$3.5 billion by 2030. At the same time, the incidence of
thyroid cancer is increasing more rapidly than that of any
other cancer and is on track to become the third most common
cancer in women.
study, Dr. Brito and his colleagues drew on data from the
Rochester Epidemiology Project. They analyzed the records of
566 men and women who were diagnosed with thyroid cancer in
Olmsted County, Minnesota, between 1935 and 2012.
Specifically, they examined the number of new cases of thyroid
cancer, the deaths due to the disease and the method of
found that the number of new cases of thyroid cancer doubled
in recent years – from 7.1 per 100,000 people from 1990 to
1999 to 13.7 per 100,000 people from 2000 to 2012. Over the
same period, the number of new patients with thyroid cancer
presenting with symptoms of thyroid cancer remained the same.
In contrast, the number of new cases of silent thyroid cancer
— the kind for which patients have no symptoms — almost
quadrupled. The proportion of patients with thyroid cancer who
die of the disease has not changed since 1935.
study found that the most frequent reasons for identifying
silent thyroid cancer were review of thyroid tissue removed
for benign conditions (14 percent); incidental discovery
during an imaging test (19 percent); and investigations of
patients with symptoms or palpable nodules that were clearly
not associated with thyroid cancer, but triggered the use of
imaging tests of the neck (27 percent).
are facing an epidemic of diagnosis in thyroid cancer,"
says Dr. Brito. "Now that we know where all these new
cases are coming from, we can design strategies to identify
patients with thyroid cancer who can benefit from our
treatment without condemning other patients to unnecessary
tests, treatment, suffering and costs."
say one approach to curtail the detection of these lesions
would be to limit the use of certain imaging technologies.
Another tactic would be to engage patients in deliberating
about their treatment options. In many cases, active
surveillance may be preferred over surgery by patients with
small, relatively benign cancers that could take decades to
grow to any appreciable size or cause life-threatening
Brito thinks something as simple as not using the word
"cancer" to refer to these small and silent thyroid
lesions could reduce the number of unnecessary treatments for
patients with a more favorable prognosis. Rather than calling
these lesions thyroid cancer, he would recommend a less
emotionally charged term, such as papillary lesions of