The USPSTF today once more
made an important update to its 2009 U.S. Preventive Services Task Force
(USPSTF) recommendation on screening for breast cancer. The USPSTF recommends biennial screening
mammography for women aged 50 to 74 years. (B recommendation).These recommendations were published in the on-line
issue of Annals of Internal Medicine on January 12, 2016.
Breast Cancer
Screening Recommendations for Average-Risk Women
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Agency issuing guidelines
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Recommendations
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USPSTF 2015
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40–49 years
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Screening decision should be an
informed, individual one, after she weighs the potential benefit against the
potential harms.( C recommendations )
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50–74 years
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Mammography every 2 years (B recommendation)
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≥75 years
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Data were not
sufficient to establish the benefits of mammography screening in women aged
75 years or older.( I statement)
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ACOG
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40 years ≥
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Annual mammograms beginning at age 40.
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ACS
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45 years
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Annual screening beginning at age 45
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45-54 years
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Annual screening
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55 and older
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Transition to biennial screening or have
the opportunity to continue screening annually depending upon personal
preference. Women should continue screening mammography as long as their
overall health is good and they have a life expectancy of 10 years or longer
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NCCN
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40 years ≥
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Clinical breast exam every 6-12 + annual mammogram
beginning at age 40years.
Upper age limit for screening not established; screening
can continue if the woman is in good health and is expected to live at least
10 more years
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Breast cancer is
the second-leading cause of cancer death among women in the United States.
In 2015, an
estimated 232 000 women were diagnosed with the disease and 40,000 women
died of it.
There are
approximately 125 new cases of breast cancer and about 22 deaths per
100 000 U.S.
women each year. The mean age at diagnosis has remained unchanged at 64 years
since the late 1970s.
It is most
frequently diagnosed among women aged 55 to 64 years, and the median age of
death from breast cancer is 68 years.
Across all ages,
screening mammography has a sensitivity of approximately 77% to 95% and a
specificity of about 94% to 97%
Dr.Christine Laine praises the USPSTF in an accompanying
editorial saying that “The
USPSTF did a difficult job well, considering updated evidence reviews, fuller
panoply of potential harms, and tradeoffs of different screening strategies.”
She also said that
“ Although for many years the dogma was that women should have mammograms “once
a year for a lifetime” starting at age 40 years, current evidence shows that
the balance of risks and benefits of screening, particularly among women in
their 40s, warrants more nuanced decision making. Potential harms of over
diagnosis and overtreatment of lesions with little progressive potential and
harms of false-positive screening results with unnecessary biopsies and
multiple repeated examinations must be considered”.
The following
recommendation (originally issued in 2009) still stands: Each average-risk
woman between the ages of 40 and 49 years should make her own decision about
whether to have a mammogram, based on her personal balancing of the benefits
and harms of screening (a grade “C” recommendation).
Benefit of Screening
Over a 10-year
period, screening 10 000 women aged 60 to 69 years will result in 21 (95%
CI, 11 to 32) fewer breast cancer deaths. The benefit is smaller in younger
women: Screening 10 000 women aged 50 to 59 years will result in 8 (CI, 2
to 17) fewer breast cancer deaths, and screening 10 000 women aged 40 to
49 years will result in 3 (CI, 0 to 9) fewer breast cancer deaths.
Harms of screening
The harms of screening are over diagnosis and over screening
that is diagnosis and treatment of non invasive and invasive cancer that would
never have been detected in the absence of screening. Existing technology does
not allow us to segregate with precision about how much is over diagnosis and
how much was real diagnosis.
The best estimates
from randomized, controlled trials (RCTs) evaluating the effect of mammography
screening on breast cancer mortality suggest that 1 in 5 women diagnosed with
breast cancer over approximately 10 years will be over diagnosed.
Based on data from the
National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER)
Program: The baseline breast cancer incidence rate was 105 to 111 cases per
100 000 women (depending on whether one considers invasive disease or
invasive plus noninvasive disease together). With the widespread diffusion of
mammography screening in last 30 years, this rate increased to 165 cases of
noninvasive plus invasive disease per 100 000 women in 2011 (an excess of
54 to 60 cases per 100 000 women, or about a 50% increase).
Breast cancer
mortality rates have declined at a slower rate, from 31 to 22 cases (or a
reduction of 9 deaths) per 100,000 women over the same time period.
The USPSTF
concludes that while there are harms of mammography, the benefit of screening
mammography outweighs the harms by at least a moderate amount from age 50 to 74
years and is greatest for women in their 60s. For women in their 40s, the
number who benefit from starting regular screening mammography is smaller and
the number experiencing harm is larger compared with older women.
The current
recommendations by USPSTF are based upon modeling studies conducted in support by the Cancer
Intervention and Surveillance Modeling Network (CISNET). The investigators at CISNET evaluated data from six
models that were grouped according to various screening strategies, various
starting age and frequency. The model
with no screening served as reference.
It was seen that strategies
involving screening every 2 years were consistently the most efficient for
women at average risk for breast cancer.
The models showed that for women in the age group 50 to 74
years, biennial screening would prevent a median of seven breast-cancer deaths,
compared with no screening vs. if the screening started at age 40, three
additional breast cancer deaths would be prevented, but there would be 1988
more false-positive results and seven more over diagnoses for every 1000 women
screened.
Dissatisfaction with the
updated guidelines.
Many of the National agencies like National Comprehensive
Cancer Network (NCCN) and M.D. Anderson Cancer Center are continue to screen
women annually beginning at age 40 till she is within a decade of the predicted
end of her life according to Therese Bevers, MD, medical director of the Cancer
Prevention Center at the M.D. Anderson Cancer Center in Houston, and chair of
NCCN guideline panels on breast cancer screening and diagnosis and breast
cancer risk reduction.
National breast
cancer screening programs in other countries like the United Kingdom, Netherlands, Switzerland, Poland, Norway,
Luxembourg, Germany, Finland, Denmark, and Belgium offer mammography screening
every 2 to 3 years for women aged 50 up to 74 years.
References:
