Value of Mammography for Senior Women Questioned by
U.S. Task Force; Wants Research
Recommendation for breast exams from age 50
- 74, not enough known to make firm decision on women 75 up;
American Cancer Society sticks with test as long as you are healthy
Nov.
17, 2009 – New government guidelines on mammography screening for breast
cancer grabbed headlines by going against the recommendations of the
American Cancer Society for annual screening of women as young as age
40, but, not getting as much attention is their questioning of the need
for annual screening for senior women over 74, which also is counter to
the ACS recommendations issued just last month.
The U.S. Preventive Services Task Force “recommends
against routine screening mammography in women aged 40 to 49 years.”
“The decision to start regular, biennial screening
mammography before the age of 50 years should be an individual one and
take patient context into account, including the patient's values
regarding specific benefits and harms,” says the report released late
yesterday.”
Otis W. Brawley, M.D., chief medical officer,
American Cancer Society responded by saying, “The American Cancer
Society continues to recommend annual screening using mammography and
clinical breast examination for all women beginning at age 40.
Getting much less attention is what this
recommendation by the USPSTF will mean for older women.
The specific benefits
varying depending on the results of individual trials and which trials
were combined in meta-analyses.
“And
like the USPSTF, the American Cancer Society panel also found that
mammography has limitations – some women who are screened will have
false alarms; some cancers will be missed; and some women will undergo
unnecessary treatment. These limitations are somewhat greater in women
in their forties compared with women in their fifties, and somewhat
greater in women in their fifties compared with women in their sixties.
We specifically noted that the overall effectiveness of mammography
increases with increasing age.”
HHS Secretary Kathleen Sebelius says controversial
breast screening recommendation by U.S. task force is not government
policy
Nov. 19, 2009 – HHS Secretary Kathleen Sebelius
made it clear yesterday that Medicare will not be changing its policy of
paying for annual mammograms for women beginning at age 40 and
continuing for life, despite recommendations by a government task force
that women in their 40s and those age 75 and older should not get the
breast cancer test that often unless recommended by their doctor.
Read
more...
The
report noted, “The strongest evidence for the greatest benefit is
among women aged 60 to 69 years.”
The
ACS said in October, “Yearly mammograms are recommended starting
at age 40 and continuing for as long as a woman is in good health.”
So, at the upper ends of age, starting at age 75,
women are basically on their own and in the care of their personal
doctors when it comes to breast cancer screening. The USPSTF saying
there is not enough evidence to make a solid recommendation for women
age 75 or older and the ACS basically in agreement. The ACS does
recommend these older women continue with mammograms if they are in good
health.
The USPSTF report does suggest more testing should
be done to get a better understanding of the potential value in
screening women 75 and older.
“No women 75 years or older have been included in
the multiple randomized clinical trials of breast cancer screening,”
notes USPSTF.
“Breast cancer is a leading cause of death in older
women, which might suggest that the benefits of screening could be
important at this age. However, 3 facts suggest that benefits from
screening would probably be smaller for this age group than for women
aged 60 to 69 years and probably decrease with increasing age:
1) the benefits of screening occur only several
years after the actual screening test, whereas the percentage of women
who survive long enough to benefit decreases with age;
2) a higher percentage of the type of breast cancer
detected in this age group is the more easily treated estrogen
receptor-positive type; and
3) women of this age are at much greater risk for
dying of other conditions that would not be affected by breast cancer
screening.
Yet, the USPSTF suggests, “A series of randomized
clinical trials that would compare the results of stopping breast cancer
screening at different ages (by first comparing stopping screening at
age 75 years with continued screening, and then further comparing
stopping screening at earlier ages, depending on the results of the
first study) would be ethical and informative.”
Below is a summary of the USPSTF report:
● The USPSTF recommends against routine
screening mammography in women aged 40 to 49 years. The decision to
start regular, biennial screening mammography before the age of 50 years
should be an individual one and take patient context into account,
including the patient's values regarding specific benefits and harms.
● The USPSTF recommends biennial screening
mammography for women aged 50 to 74 years.
● The USPSTF concludes that the current evidence
is insufficient to assess the additional benefits and harms of screening
mammography in women 75 years or older.
● The USPSTF recommends against teaching
breast self-examination (BSE).
● The USPSTF concludes that the current evidence
is insufficient to assess the additional benefits and harms of
clinical breast examination (CBE) beyond screening mammography in
women 40 years or older.
● The USPSTF concludes that the current evidence
is insufficient to assess the additional benefits and harms of either
digital mammography or magnetic resonance imaging (MRI) instead of film
mammography as screening modalities for breast cancer.
Summary Statement of USPSTF
Breast cancer is the second-leading cause of cancer
death among women in the United States. Widespread use of screening,
along with treatment advances in recent years, have been credited with
significant reductions in breast cancer mortality.
Detection
Mammography, as well as physical examination of the
breasts (CBE and BSE), can detect presymptomatic breast cancer. Because
of its demonstrated effectiveness in randomized, controlled trials of
screening, film mammography is the standard for detecting breast cancer;
in 2002, the USPSTF found convincing evidence of its adequate
sensitivity and specificity.
Benefits of Detection and Early Intervention
● There is convincing evidence that screening
with film mammography reduces breast cancer mortality, with a greater
absolute reduction for women aged 50 to 74 years than for women aged 40
to 49 years.
● The strongest evidence for the greatest
benefit is among women aged 60 to 69 years.
● Among women 75 years or older, evidence of
benefits of mammography is lacking.
● Adequate evidence suggests that teaching BSE
(self exam) does not reduce breast cancer mortality.
● The evidence for additional effects of CBE
beyond mammography on breast cancer mortality is inadequate.
● The evidence for benefits of digital
mammography and MRI of the breast, as a substitute for film mammography,
is also lacking.
Harms of Detection and Early Intervention
The harms resulting from screening for breast
cancer include psychological harms, unnecessary imaging tests and
biopsies in women without cancer, and inconvenience due to
false-positive screening results. Furthermore, one must also consider
the harms associated with treatment of cancer that would not become
clinically apparent during a woman's lifetime (overdiagnosis), as well
as the harms of unnecessary earlier treatment of breast cancer that
would have become clinically apparent but would not have shortened a
woman's life. Radiation exposure (from radiologic tests), although a
minor concern, is also a consideration.
Adequate evidence suggests that the overall harms
associated with mammography are moderate for every age group considered,
although the main components of the harms shift over time. Although
false-positive test results, overdiagnosis, and unnecessary earlier
treatment are problems for all age groups, false-positive results are
more common for women aged 40 to 49 years, whereas overdiagnosis is a
greater concern for women in the older age groups.
There is adequate evidence that teaching BSE is
associated with harms that are at least small. There is inadequate
evidence concerning harms of CBE.
USPSTF Assessment
The USPSTF has reached the following conclusions:
For biennial screening mammography in women aged 40
to 49 years, there is moderate certainty that the net benefit is small.
Although the USPSTF recognizes that the benefit of screening seems
equivalent for women aged 40 to 49 years and 50 to 59 years, the
incidence of breast cancer and the consequences differ. The USPSTF
emphasizes the adverse consequences for most women—who will not develop
breast cancer—and therefore use the number needed to screen to save 1
life as its metric.
By this metric, the USPSTF concludes that there is
moderate evidence that the net benefit is small for women aged 40 to 49
years.
● For biennial screening mammography in women
aged 50 to 74 years, there is moderate certainty that the net benefit is
moderate.
● For screening mammography in women 75 years or
older, evidence is lacking and the balance of benefits and harms cannot
be determined.
● For the teaching of BSE, there is moderate
certainty that the harms outweigh the benefits.
● For CBE as a supplement to mammography,
evidence is lacking and the balance of benefits and harms cannot be
determined.
● For digital mammography and MRI as a
replacement for mammography, the evidence is lacking and the balance of
benefits and harms cannot be determined.
Clinical Considerations
Patient Population Under Consideration
This recommendation statement applies to women 40
years or older who are not at increased risk for breast cancer by virtue
of a known underlying genetic mutation or a history of chest radiation.
Assessment of Risk
Increasing age is the most important risk factor
for breast cancer for most women. Women without known deleterious
genetic mutations (such as BRCA1 or BRCA2) may still have other
demographic, physical, or historical risk factors for breast cancer, but
none conveys a clinically important absolute increased risk for cancer.
Screening Tests
In recent decades, the early detection of breast
cancer has been accomplished by physical examination by a clinician
(CBE), by a woman herself (BSE), or by mammography. Standardization of
mammography practices enacted by the Mammography Quality Standards Act
have led to improved mammography quality. Clinicians should refer
patients to Mammography Quality Standards Act-certified facilities, a
listing of which is available at
http://www.fda.gov/cdrh/mammography/certified.html.
Screening Intervals
In trials that demonstrated the effectiveness of
mammography in decreasing breast cancer mortality, screening was
performed every 12 to 33 months. The evidence reviewed by the USPSTF
indicates that a large proportion of the benefit of screening
mammography is maintained by biennial screening, and changing from
annual to biennial screening is likely to reduce the harms of
mammography screening by nearly half. At the same time, benefit may be
reduced when extending the interval beyond 24 months; therefore the
USPSTF recommends biennial screening.
Treatment
Effective treatments, including radiation,
chemotherapy (including hormonal treatment), and surgery, are available
for invasive carcinoma. Although the standard treatments women receive
for ductal carcinoma in situ (DCIS) include surgical approaches as well
as radiation and hormonal therapy, considerable debate exists about the
optimal treatment strategy for this condition.
Considerations for Practice Regarding I Statements
Clinical Breast Examination
Potential Preventable Burden. The evidence for CBE,
although indirect, suggests that CBE may detect a substantial proportion
of cases of cancer if it is the only screening test available. In parts
of the world where mammography is infeasible or unavailable (such as
India), CBE is being investigated in this way.
Potential Harms. The potential harms of CBE are
thought to be small but include false-positive test results, which lead
to anxiety and breast cancer worry, as well as repeated visits and
unwarranted imaging and biopsies.
Costs. The principal cost of CBE is the opportunity
cost incurred by clinicians in the patient encounter.
Current Practice. Surveys suggest that the CBE
technique used in the United States currently lacks a standard approach
and reporting standards. Clinicians who are committed to spending the
time on CBE would benefit their patients by considering the evidence in
favor of a structured, standardized examination (.
Digital Mammography
Potential Preventable Burden. Digital mammography
detects some cases of cancer not identified by film mammography; film
mammography detects some cases of cancer not identified by digital
mammography. Overall detection is similar for many women. For women who
are younger than 50 years or have dense breast tissue, overall detection
is somewhat higher with digital mammography. It is not clear whether
this additional detection would lead to reduced mortality from breast
cancer.
Potential Harms. The possibility of false-positive
test results is similar for film and digital mammography. It is
uncertain whether overdiagnosis occurs more with digital mammography
than with film mammography.
Costs. Digital mammography is more expensive than
film mammography.
Current Practice. Some clinical practices are now
switching their mammography equipment from film to digital. This may
curtail the availability of film mammography in some areas.
Magnetic Resonance Imaging
Potential Preventable Burden. Studies of the use of
contrast-enhanced MRI for breast cancer screening have been conducted
only in very high-risk populations. In these studies, MRI detected more
cases of cancer than did mammography. It is unknown whether detecting
these additional cases of cancer would lead to reduced breast cancer
mortality.
Potential Harms. Contrast-enhanced MRI requires the
injection of contrast material. Studies of MRI screening have shown that
MRI yields many more false-positive results than does mammography.
Magnetic resonance imaging has the potential to be associated with a
greater degree of overdiagnosis than mammography.
Costs. Magnetic resonance imaging is much more
expensive than either film or digital mammography.
Current Practice. Magnetic resonance imaging is not
currently used for screening women at average risk for breast cancer.
Screening Mammography in Women 75 Years or Older
Potential Preventable Burden. No women 75 years or
older have been included in the multiple randomized clinical trials of
breast cancer screening. Breast cancer is a leading cause of death in
older women, which might suggest that the benefits of screening could be
important at this age. However, 3 facts suggest that benefits from
screening would probably be smaller for this age group than for women
aged 60 to 69 years and probably decrease with increasing age: 1) the
benefits of screening occur only several years after the actual
screening test, whereas the percentage of women who survive long enough
to benefit decreases with age; 2) a higher percentage of the type of
breast cancer detected in this age group is the more easily treated
estrogen receptor-positive type; and 3) women of this age are at much
greater risk for dying of other conditions that would not be affected by
breast cancer screening.
Potential Harms. Screening detects not only cancer
that could lead to a woman's death but also cancer that will not shorten
a woman's life. Women cannot benefit from—but can be harmed by—the
discovery and treatment of this second type of cancer, which includes
both cancer that might some day become clinically apparent and cancer
that never will. Detection of cancer that would never have become
clinically apparent is called overdiagnosis, and it is usually followed
by overtreatment. Because of a shortened life span among women 75 years
or older, the probability of overdiagnosis and unnecessary earlier
treatment increases dramatically after about age 70 or 75 years.
Overdiagnosis and unnecessary earlier treatment are important potential
harms from screening women in this age group.
Current Practice. Studies show that many women
75 years or older are currently being screened.
Useful Resources
Other USPSTF recommendations on screening for
genetic susceptibility for breast cancer and chemoprevention of breast
cancer are available on the Agency for Healthcare Research and Quality
Web site(http://www.preventiveservices.ahrq.gov).
Other Considerations
Implementation
The Task Force on Community Preventive Services has
reviewed the evidence on methods to increase breast cancer screening,
including reminder systems and other interventions .
Explanation of Change in Recommendation
The 2002 USPSTF issued a B recommendation for
screening mammography for women 40 years or older. However, it went on
to say:
The precise age at which the benefits from
screening mammography justify the potential harms is a subjective
judgment and should take into account patient preferences. Clinicians
should inform women about the potential benefits (reduced chance of
dying from breast cancer), potential harms (for example, false-positive
results, unnecessary biopsies), and limitations of the test that apply
to women their age. Clinicians should tell women that the balance of
benefits and potential harms of mammography improves with increasing age
for women between the ages of 40 and 70
The updated USPSTF recommendation endorses this
approach to deciding when to start screening. However, the current
USPSTF is now further informed by a new systematic review, which
incorporates a new randomized, controlled trial that estimates the
"number needed to invite for screening to extend one woman's life" as
1904 for women aged 40 to 49 years and 1339 for women aged 50 to 59
years.
Although the relative risk reduction is nearly
identical (15% and 14%) for these 2 age groups, the risk for breast
cancer increases steeply with age starting at age 40 years. Thus, the
absolute risk reduction from screening (as shown by the number needed to
invite to screen) is greater for women aged 50 to 59 years than for
those aged 40 to 49 years.
The current USPSTF statement is also informed by
the Cancer Intervention and Surveillance Modeling Network (CISNET)
modeling studies that accompany this recommendation. The Task Force
considered both "mortality" and "life-years gained" outcomes. In this
case, given that the age groups (40 to 49 years and 50 to 59 years) are
adjacent, the Task Force elected to emphasize the mortality outcomes
from the modeling studies.
Of the 8 screening strategies found most efficient,
6 start at age 50 years rather than age 40 years. The frontier curves
for the mortality outcome show only small gains but larger numbers of
mammograms required when screening is started at age 40 years versus age
50 years.
In conclusion, the USPSTF reasoned that the
additional benefit gained by starting screening at age 40 years rather
than at age 50 years is small, and that moderate harms from screening
remain at any age. This leads to the C recommendation. The USPSTF notes
that a "C" grade is a recommendation against routine screening of women
aged 40 to 49 years. The Task Force encourages individualized, informed
decision making about when to start mammography screening.
Research Needs and Gaps
A series of randomized clinical trials that would
compare the results of stopping breast cancer screening at different
ages (by first comparing stopping screening at age 75 years with
continued screening, and then further comparing stopping screening at
earlier ages, depending on the results of the first study) would be
ethical and informative.
Extended follow-up of this type of study might also
provide useful information about overdiagnosis in this age group. In
general, more studies of overdiagnosis, including comparisons of
lifetime breast cancer incidence among similar screened and unscreened
women, would be helpful. Studies on overdiagnosis might also include
long-term follow-up of women with probable missed cases of DCIS on the
basis of microcalcifications that were missed in an earlier mammogram.
Such studies could provide the percentage of these women who develop
invasive breast cancer over the next 10 or more years.
Randomized clinical trials of film versus digital
mammography among women with dense breast tissue, with sufficient
follow-up to detect stage shifts (reductions of late-stage cancer) or
decreases in clinical interval cases, would also be ethical and helpful.
Better understanding of certain facets of tumor
biology is needed, particularly how age, race, breast density, and other
factors may predispose certain women toward tumors with faster growth
rates and greater lethality. This would improve the ability to determine
at diagnosis which patients can be treated minimally.
Breast cancer is the most frequently diagnosed
cancer in women in the United States, not including skin cancer, and is
second only to lung cancer as a cause of cancer deaths. In 2008, an
estimated 182,460 cases of invasive cancer and 67,770 cases of in situ
breast cancer were diagnosed and 40,480 breast cancer deaths occurred.
The National Cancer Institute, on the basis of Surveillance Epidemiology
and End Result data, estimates the lifetime risk for a woman to develop
breast cancer at 12%.
T
he risk for breast cancer increases with age. The 10-year risk for
breast cancer is 1 in 69 for a woman at age 40 years, 1 in 42 at age 50
years, and 1 in 29 at age 60 years. The incidence rate of breast cancer
has increased since the 1970s; however, recent data show that this rate
seems to be decreasing, both overall and on an age-adjusted basis. The
incidence rate in 2003 was 124.2 per 100,000 women, a 6.7% decrease from
the previous year.
Discontinuation of hormone replacement therapy may be largely
responsible for this observed decrease, although slowed growth or even a decline in screening
mammography also may have contributed. Breast cancer mortality has been
decreasing since 1990 by 2.3% per year overall and by 3.3% for women
aged 40 to 50 years. This decrease is largely attributed to the
combination of mammography screening with improved treatment.
Scope of Review
The systematic evidence review undertaken in
support of this recommendation addressed the efficacy of 5 breast cancer screening methods for reducing
breast cancer mortality—film mammography, CBE, BSE, digital mammography,
and MRI—by using published reports of randomized, controlled screening
trials and specifically updated information from mammography trials
among women in the age groups of 40 to 49 years and 70 years or older.
Information on harms of breast cancer screening, such as false-positive
test results, pain, anxiety, and biopsy rates, were sought from multiple
sources, including systematic reviews, meta-analyses, and recently
published literature. To assess the follow-up testing and other outcomes
of a mammography screening program, the reviewers included data from the
Breast Cancer Surveillance Consortium from 2000 to 2005.
In addition to the systematic review of screening
tests, the USPSTF requested a report from the CISNET Breast Cancer
Modeling Group to provide data from comparative decision models on
optimal starting and stopping ages and intervals for screening
mammography.
Accuracy of Screening Tests
Mammography, CBE, and BSE are recognized approaches
for breast cancer screening. Since the 2002 USPSTF recommendation
statement, digital (as opposed to film-based) mammography has been
increasingly used, and MRI is being used with greater frequency for
screening women at increased risk for breast cancer.
The sensitivity of mammography screening is 77% to
95%, whereas specificity is 94% to 97%.
Multiple factors, including age, time since last examination, breast
tissue density, equipment, and the skill of the interpreting radiologist
can affect sensitivity and specificity.
A single, large comparison study of film and
digital mammography
demonstrated similar diagnostic accuracy for the 2 methods, although
digital mammography was better at detecting lesions in women who were
younger than 50 years or premenopausal or had radiographically dense
breasts.
Studies of MRI in high-risk women without cancer
showed that MRI has a sensitivity of 71% to 100% and a specificity of
81% to 97%; MRI is therefore recommended by the American Cancer Society
for women at high risk for breast cancer. However, no studies have been
done on using MRI to screen women at average risk.
Clinical breast examination has a sensitivity of
40% to 69% and a specificity in the range of 88% to 99%. For BSE,
sensitivity ranges from 12% to 41%, lower than that of CBE and
mammography, and is age-dependent (16).
Effectiveness of Early Detection
The newly updated meta-analysis by Nelson and
colleagues (7)
confirms an earlier finding (16)
that screening mammography reduces mortality. Improvements in the
relative risk (RR) for death due to breast cancer for women aged 39 to
49 years and 50 to 59 years are similar at 0.85 (95% CI, 0.75 to 0.96)
and 0.86 (CI, 0.75 to 0.99), respectively. An even greater improvement
was found for women aged 60 to 69 years (RR, 0.68 [CI, 0.54 to 0.87]).
Results were uncertain for older women, with a new report from a
previously included trial with longer follow-up data showing an RR of
1.12 (CI, 0.73 to 1.72) for breast cancer death associated with
screening women aged 70 to 74 years (based on a small number of
participants). At the time of the previous meta-analysis, data from 2
trials showed an RR of 0.78 (CI, 0.62 to 0.99) for breast cancer death
in screened women aged 65 to 74 years (16).
Mortality reduction and life-years gained (8)
were both considered important outcomes of screening in forming this
recommendation; in the end, mortality reduction as observed in trials
was the metric chosen to express the benefits of screening in each age
group. Digital mammography has been shown to perform similarly to film
mammography, although it has never been studied in relation to health
outcomes. Magnetic resonance imaging has not been evaluated for its
potential benefit in screening average-risk women. Clinical breast
examination is inexpensive and easy to perform; however, few studies
have compared the effectiveness of CBE with that of no screening and
none has examined CBE and mammography versus mammography alone. Two
large trials of teaching BSE outside the United States (7)
demonstrated no mortality benefit in the intervention groups.
Potential Harms of Screening
Mammography
False-positive results are common with mammography
and can cause anxiety and lead to additional imaging studies and
invasive procedures (such as biopsy or fine-needle aspiration).
False-positive results and accompanying additional imaging studies are
more common in younger women. Biopsies may occur as a consequence of
false-positive mammography results; biopsy rates are more common among
older women. Anxiety, distress, and other psychosocial effects can exist
with abnormal mammography results but fortunately are usually transient,
and some research suggests that these effects are not a barrier to
screening. False-negative results occur at a relatively low rate for all
ages, but are slightly higher in women older than 70 years. Other
potential harms, such as pain caused by the procedure, exist but are
thought to have little effect on mammography use.
Overdiagnosis can occur when screening detects
early-stage invasive breast cancer or DCIS in a woman, typically older,
who is likely to die from another cause before the breast cancer would
be clinically detected. Overdiagnosis can also occur in younger women if
a detected DCIS or other early-stage lesion never progresses to invasive
cancer. Methods for estimating overdiagnosis at a population level are
not well established, and thus the proportion of all detected DCIS
lesions that constitute overdiagnosis is uncertain (7).
Similarly, unnecessary earlier treatment can occur at any age when
screening detects a slower-growing cancer that would have eventually
become clinically apparent but would never have caused death.
Radiation exposure may increase the risk for breast
cancer, but usually only at much higher doses than those used in
mammography, although regular mammography could contribute to cumulative
radiation doses from additional imaging for other reasons
Digital Mammography and Magnetic Resonance Imaging
Digital mammography can be expected to have harms
similar to those of film mammography. No studies have evaluated MRI
screening of average-risk women; in theory, because MRI could be
considerably less specific than mammography screening, it could
potentially be associated with higher biopsy rates and greater degrees
of overdiagnosis if used in low-risk populations.
Clinical Breast Examination
A theoretical harm of CBE is that its lower
specificity than that of mammography may result in more women undergoing
biopsy. Few data are available to evaluate harms associated with CBE.
Breast Self-Examination
One study indicated that anxiety was not a concern
with BSE. The 2 available trials
indicated that more additional imaging procedures and biopsies were done
for women who performed BSE than for control participants.
Estimate of Magnitude of Net Benefit
In 2002, the USPSTF concluded that there was fair
evidence that mammography screening every 12 to 33 months could
significantly reduce breast cancer mortality. The evidence was strongest
for women aged 50 to 69 years, with weaker evidence supporting
mammography screening for women aged 40 to 49 years. Since that
recommendation, 1 new trial and updated data from an older study have
been published that specifically address screening in women in the
younger age group. T
hese findings were combined in an updated
meta-analysis, which resulted in an RR for breast cancer death of 0.85
(CI, 0.75 to 0.96; 8 trials) and a number needed to invite for screening
of 1904 (CI, 929 to 6378) to prevent 1 breast cancer death in women aged
39 to 49 years.
A meta-analysis of 6 trials among women aged 50 to 59
years and 2 trials among women aged 60 to 69 years provided pooled RRs
for breast cancer death in the screened group of 0.86 (CI, 0.75 to 0.99;
number needed to invite, 1339 [CI, 322 to 7455]) and 0.68 (CI, 0.54 to
0.87; number needed to invite, 377 [CI, 230 to 1050]), respectively.
Only 1 study provided data on women older than 70 years, yielding an RR
of 1.12 (CI, 0.73 to 1.72), although an RR of 0.78 (CI, 0.62 to 0.99)
was found for women aged 65 to 74 years by combining the results of 2
studies used in the 2002 review.
A decision analysis performed for the USPSTF
projected that biennial screening produced 70% to 99% of the benefit of
annual screening, with a significant reduction in the number of
mammograms required and therefore a decreased risk for harms. Screening
between the ages of 50 and 69 years produced a projected 17% (range, 15%
to 23%) reduction in mortality (compared with no screening), whereas
extending the age range produced only minor improvements (additional 3%
reduction from starting at age 40 years and 7% from extending to age 79
years).
The USPSTF noted with moderate certainty that the
net benefits of screening mammography in women aged 50 to 74 years were
at least moderate, and that the greatest benefits were seen in women
aged 60 to 69 years. For women aged 40 to 49 years, the USPSTF had
moderate certainty that the net benefits were small. Because of the
uncertainties related to harms of screening, particularly overdiagnosis,
and the near total lack of trial data for older women, the USPSTF had
low certainty about the net benefits of screening mammography for women
75 years or older.
How Does Evidence Fit With Biological
Understanding?
Current knowledge about the development of breast
cancer is limited. The effectiveness of screening mammography seen in
trials presumably results from the early detection of smaller,
earlier-stage tumors, which are more responsive to available treatments.
Although the most common breast cancer occurs in the epithelial cells
that line the duct system of the gland (ductal carcinoma), the sequence
of development of invasive cancer is not entirely known. For example,
DCIS does not always represent a precursor to invasive ductal cancer.
Studies of women with untreated DCIS showed progression to invasive
disease in half or fewer of the cases.
Because DCIS is often found only
by mammography, its incidence has increased steadily since the advent of
widespread screening mammography. In 1983, 4900 cases of DCIS were
diagnosed; by 2008, that number was expected to be 67,770.
Because the likelihood that DCIS will progress to invasive cancer is
unknown, surgical removal—with or without adjuvant treatment - may
represent overdiagnosis or overtreatment. Lobular carcinoma in situ, in
contrast, is not considered a true precursor lesion but connotes a
higher risk for subsequent invasive lobular or ductal cancer in either
breast.
Lobular carcinoma in situ is often multifocal, appearing in
several distinct locations. Knowledge of what determines the rapidity
with which invasive cancer can spread (tumor characteristics, host
factors, hormonal triggers) is limited. Because of these elements of
biological uncertainty, it is clear that lesion sensitivity alone is not
a sufficient metric for assessing effectiveness of new screening
methods.
Update of Previous USPSTF Recommendation
This recommendation updates the 2002 recommendation
by providing specific recommendations for mammography screening by age.
The previous recommendation statement recommended screening mammography
every 1 to 2 years for all women older than 40 years. The USPSTF now
recommends against routine screening of women aged 40 to 49 years (C
recommention), recommends biennial screening mammography for all women
aged 50 to 74 years (B recommendation), and provides an I statement
regarding screening of women older than 75 years. The USPSTF now
recommends against teaching BSE (D recommendation), replacing the
previous statement of insufficient evidence. The evidence for CBE
continues to be assessed as insufficient. Digital mammography and MRI as
screening tools were not addressed in the 2002 recommendation statement;
the USPSTF concludes that the evidence is insufficient to assess the
harms or benefits of these methods for screening.
Recommendations of Others
Numerous organizations have provided breast cancer
screening recommendations. These recommendations are summarized below.
All recommendations are for women not at increased risk for breast
cancer.
In 2003, the American Cancer Society recommended
annual mammography beginning at age 40 years, annual CBE after the age
of 40 years. It does not recommend MRI for women at average risk for
breast cancer and states that there is insufficient evidence to
recommend BSE.
The American Medical Association, in 2002, and the
National Comprehensive Cancer Network, in 2009, have made
recommendations similar to those of the American Cancer Society, except
for the inclusion of a positive recommendation for BSE.
The American Academy of Family Physicians has
endorsed the USPSTF recommendation on breast cancer screening in the
past. The American College of Physicians recommended in 2007 that
screening mammography decisions in women aged 40 to 49 years should be
based on individualized assessment of risk for breast cancer; that
clinicians should inform women aged 40 to 49 years about the potential
benefits and harms of screening mammography; and that clinicians should
base screening mammography decisions on benefits and harms of screening,
as well as on a woman's preferences and breast cancer risk profile.
In 2001, the Canadian Task Force on Preventive
Health Care recommended mammography every 1 to 2 years beginning at the
age of 40 years and recommended CBE as part of a periodic evaluation
(every 1 to 3 years) for women aged 50 to 69 years. It does not
recommend BSE.
In 2003, the American College of Obstetrics and
Gynecology recommended mammography every 1 to 2 years for women aged 40
to 49 years and annually after the age of 50 years. It recommended CBE
for all women and noted that BSE can be recommended.
In 2009, the World Health Organization recommended
mammography every 1 to 2 years for women aged 50 to 69 years, but does
not recommend CBE or BSE.
Members of the U.S. Preventive Services Task
Force
Members of the U.S. Preventive Services Task Force*
are Ned Calonge, MD, MPH, Chair (Colorado Department of Public Health
and Environment, Denver, Colorado); Diana B. Petitti, MD, MPH,
Vice-Chair (Arizona State University, Phoenix, Arizona); Thomas G.
DeWitt, MD (Children's Hospital Medical Center, Cincinnati, Ohio); Allen
J. Dietrich, MD (Dartmouth Medical School, Hanover, New Hampshire);
Kimberly D. Gregory, MD, MPH (Cedars-Sinai Medical Center, Los Angeles,
California); David Grossman, MD (Group Health Cooperative, Seattle,
Washington); George Isham, MD, MS (HealthPartners, Minneapolis,
Minnesota); Michael L. LeFevre, MD, MSPH (University of Missouri School
of Medicine, Columbia, Missouri); Rosanne M. Leipzig, MD, PhD (Mount
Sinai School of Medicine, New York, New York); Lucy N. Marion, PhD, RN
(School of Nursing, Medical College of Georgia, Augusta, Georgia);
Bernadette Melnyk, PhD, RN (Arizona State University College of Nursing
& Health Innovation, Phoenix, Arizona); Virginia A. Moyer, MD, MPH
(Baylor College of Medicine, Houston, Texas); Judith K. Ockene, PhD
(University of Massachusetts Medical School, Worcester, Massachusetts);
George F. Sawaya, MD (University of California, San Francisco, San
Francisco, California); J. Sanford Schwartz, MD (University of
Pennsylvania Medical School and the Wharton School, Philadelphia,
Pennsylvania); and Timothy Wilt, MD, MPH (University of Minnesota
Department of Medicine and Minneapolis Veterans Affairs Medical Center,
Minneapolis, Minnesota).
*Members of the Task Force at the time this
recommendation was finalized. For a list of current Task Force members,
go to
http://www.ahrq.gov/clinic/uspstfab.htm.
Disclaimer: Recommendations made by the USPSTF are
independent of the U.S. government. They should not be construed as an
official position of the Agency for Healthcare Research and Quality or
the U.S. Department of Health and Human Services.
Source: U.S. Preventive Services Task Force.
Screening for breast cancer: U.S. Preventive Services Task Force
Recommendation Statement. Ann Intern Med 2009;151:716-726.
Nov.
17, 2009 – New government guidelines on mammography screening for breast
cancer grabbed headlines by going against the recommendations of the
American Cancer Society for annual screening of women as young as age
40, but, not getting as much attention is their questioning of the need
for annual screening for senior women over 74, which also is counter to
the ACS recommendations issued just last month.
