A new report by the International Agency for
Research on Cancer(IARC) in collaboration with the
Aviano National Cancer Institute in Italy shows that
the growing epidemic of thyroid cancer
reported in recent decades in several high-income
countries is largely due to overdiagnosis (i.e. the
diagnosis of tumours that are very unlikely to cause
symptoms or death during a person’s lifetime).
Breast Cancer
For every life saved from breast cancer by the
Breast Cancer Screening Programme, five women are
over-diagnosed, and have to go through an operation
to remove a tumour that otherwise never would have
caused problems. This is one of several conclusions
to an evaluation done by several Scandinavian
researchers.
Breast cancer is routinely overdiagnosed
(2015-07-17)
Link...
Prostate cancer
For men with prostate cancer diagnosed through PSA
screening, between 11.3% and 19.8% will receive a
false-positive diagnosis, and 40% to 56% will be
affected by overdiagnosis leading to invasive
treatment.
Treatment such as surgery can cause postoperative
complications, such as infection (in 11% to 21% of
men), urinary incontinence (in up to 17.8%),
erectile dysfunction (23.4%) and other
complications.
A new Canadian guideline recommends that the
prostate-specific antigen (PSA) test should not be
used to screen for prostate cancer based on evidence
that shows an increased risk of harm and uncertain
benefits. The guideline is published in CMAJ
(Canadian Medical Association Journal).
New prostate cancer screening guideline recommends
not using PSA test (2014/11/18)
Link...
Thyroid cancer
The article, published in The New England Journal of
Medicine, used high-quality cancer registry data
from IARC’s reference publication Cancer
Incidence in Five Continents to estimate the number
of overdiagnosed cases of thyroid cancer in 12
countries (Australia, Denmark, England, Finland,
France, Italy, Japan, Norway, Republic of Korea,
Scotland,Sweden, and the USA).
“Countries such as the USA, Italy, and France have
been most severely affected by overdiagnosis of
thyroid cancer since the 1980s, after the
introduction of ultrasonography, but the most recent
and striking example is the Republic of Korea,” says
Dr Salvatore Vaccarella, the IARC staff scientist
who led the study.
“A few years after ultrasonography of the thyroid
gland started being widely offered in the framework
of a population-based multi-cancer screening,
thyroid cancer has become the most commonly
diagnosed cancer in women in the Republic of Korea,
with approximately 90% of cases in 2003–2007
estimated to be due to overdiagnosis.”
The estimated fraction of overdiagnosed cases in
women during the same period ranges between 70% and
80% in Australia, France, Italy, and the USA, while
it is approximately 50% in Japan, the Nordic
countries, and England and Scotland.
In men, patterns of changing incidence were similar
but less pronounced, with far fewer cases reported.
The proportion of cases of thyroid cancer in men
that were estimated to be overdiagnoses is
approximately 70% in France, Italy, and the Republic
of Korea, 45% in Australia and the USA, and less
than 25% in all other countries examined.
In total it is estimated that more than 470,000
women and 90,000 men may have been over diagnosed
with thyroid cancer during two recent decades in the
12 countries studied.
The increasing medical surveillance and the
introduction ofnew diagnostic techniques, such as
neck ultrasonography (since the 1980s) and, more
recently, computed tomography (CT) scanning and
magnetic resonance imaging (MRI), have led to the
detection of a large number of indolent, non-lethal
diseases that exist in abundance in the thyroid
gland of healthy people of any age.
Most of these tumours are very unlikely to cause
symptoms or death.
“The majority of the overdiagnosed thyroid cancer
cases undergo total thyroidectomy and frequently
other harmful treatments, like neck lymph node
dissection and radiotherapy, without proven benefits
in terms of improved survival,” says Dr Silvia
Franceschi, one of the authors of the article.
Based on these data, the evidence in the IARC report
cautions against systematic screening of the thyroid
gland and workup of small nodules, while careful
monitoring may be a preferable option for patients
affected by low-risk tumours.
“More than half a million people are estimated to
have been overdiagnosed with thyroid cancer in the
12 countries studied,” says IARC Director Dr
Christopher Wild.
“The drastic increase in overdiagnosis and
overtreatment of thyroid cancer is already a serious
public health concern in many high-income countries,
with worrying signs of the same trend in low - and
middle-income countries.
It is therefore critical to have more research
evidence in order to evaluate the best approach to
address the epidemic of thyroid cancer and to avoid
unnecessary harm to patients.”
For more information
The International Agency for Research on Cancer IARC
- WHO
Link...
Centro di Riferimento Oncologico (CRO) – IRCCS –
National Cancer Institute
Link...
The New England Journal of Medicine
Worldwide Thyroid-Cancer Epidemic? The Increasing
Impact of Overdiagnosis
Link...
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