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Standardized Cup Sizes
Breast Size 32aa
Celebrity example Mena Suvari
Breast Size 34A
Celebrity example Audrey Hepburn
Breast Size 36B
Celebrity example Claudia Schiffer
Breast Size 34C
Celebrity example Angelina Jolie
Breast Size 40D
Celebrity example Catherine Bell
Breast Size 40F
Celebrity Example Anna Nicole
Smith Breast Size EE
Celebrity Example Dolly Parton |
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Breast cancer detected through mammography has survival advantage
Breast cancer detected through mammography has survival
advantage
August 17, 2005
HOUSTON-Women whose breast cancer was detected by screening
mammography had a significantly better prognosis than those whose
cancer was found another way-even if the cancer had already spread
to their lymph nodes, say researchers at The University of Texas M.
D. Anderson Cancer Center who looked at outcomes from randomized
screening studies of more than 150,000 women.
A likely reason for that finding is that mammography can detect
tumors that are both slower growing and less biologically lethal
than those found symptomatically, say the researchers, who
published their findings in the Aug. 17 issue of the Journal of the
National Cancer Institute.
The study is important because the survival benefit seen in this
analysis is much greater than one would expect for screen-detected
breast cancer, says the study's lead author Donald Berry, Ph.D.,
chair of the Department of Biostatistics and Applied Mathematics.
Berry is well-known for his work in designing breast cancer
clinical trials sponsored by the National Cancer Institute and for
his research in evaluating the effects of screening
mammography.
"We know that screening picks up many tumors before they can be
detected in other ways and women may benefit from early treatment,
but the advantage we found is much larger than what would be
expected from the so-called stage shift that is associated with
screening mammography," Berry says.
Based on the results, Berry suggests that method of detection
should be considered when a treatment plan for newly diagnosed
breast cancer is being devised, and that this
information also should be
collected by researchers conducting clinical trials of
experimental therapeutic strategies. "That information may be
just as important as other variables, such as the number of
positive lymph nodes. If you don't account for method of
detection, the results may not be as accurate as they would be
otherwise," Berry says.
"The important message here for clinicians and patients is that
breast cancer detected through mammography has a substantially
better survival prognosis," he says. "Of two women who have the
same age, size of tumors, and similar stage of cancer and spread to
lymph nodes, the one whose cancer was detected with mammography has
a reason to be happier than the woman whose cancer was detected
symptomatically," Berry says.
While that sounds like good news for some patients, Berry says
the conclusion should not be over interpreted.
"The paradox is that this result does not mean screening is
beneficial," he says.
"Without screening, some of the women would
not have been diagnosed with breast cancer at all, and in that
group, some of them could have avoided surgery and treatment
without detriment. The rub is that we don't know which ones they
are."
This issue has long plagued screening mammography, especially
when the detected tumors are very small and have not spread. But
this study appears to add a new element to the debate, Berry says.
"Our conclusions apply generally, and are as important in
node-negative breast cancer as they are in node-positive disease,"
he says.
In this study, researchers examined data from three large
randomized breast cancer screening trials-the
Health Insurance Plan (HIP) of
New York, which assigned about 62,000 women to screening or to a
control group; and two Canadian National Breast Cancer Screening
Studies (NBSS), which included a total of 44,790 women in the
screening groups and 44,961 women in the control groups.
They then looked only at women in these studies who were
eventually diagnosed with breast cancer, and adjusted for stage and
other tumor characteristics as a way to eliminate what is known as
"lead-time bias." Lead time is the time between when the tumor was
detected by mammography and when the tumor would have been detected
in the absence of screening.
Lead-time bias occurs because lead
time is added to the survival time of women detected by mammography
but not to women whose tumors are detected clinically, Berry says.
"Lead time is an artifact of screening and not necessarily a
benefit of screening," he says.
If lead-time bias was responsible for improved survival, and if
it was eliminated from the screening mammography group, then those
patients should have the same survival, statistically, as women
whose cancer was detected outside of mammography, the researchers
say.
But that is not what they found.
Instead they discovered that all things being equal, the method
of detection was a statistically significant independent predictor
of breast cancer survival. After adjusting for stage of disease,
patients whose breast tumors were discovered after a previous
negative mammography screen had a 53 percent greater risk of death
from the cancer than women with screen-detected cancer. Patients in
the control group (where no mammography was used) had a 36 percent
increased risk of death compared to screened patients.
"What is new here is that we found an effect that is beyond
stage shift," Berry says.
"All breast oncologists know that tumors
detected by mammography have a better survival than tumors detected
otherwise because they are smaller and more likely to be
node-negative. Our study shows that these patients are even better
off than their clinical characteristics suggest."
The difference likely is due to what is called a "length bias"
which occurs because screening detects disproportionately more
slowly growing tumors, the researchers say. This bias statistically
incorporates biological characteristics of the tumors which have
not yet been discovered, or cannot yet be easily diagnosed, Berry
says.
"If we were able to get down to the molecular level to assess
just the right factors at play in cancer
development and progression,
that might tell us how lethal a tumor is, but we can't do that
right now."
In the meantime, Berry suggests that information on method of
detection should be collected for every clinical trial in order to
improve the accuracy of findings, or at least as a way that might
account for unexpected results. "I am always surprised that
clinical trials of new agents result in better outcomes than
expected, and it may just be that screen-detected breast tumors are
becoming more common over time," he says.
University of Texas M.
D. Anderson Cancer
Center
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