Not all that long ago in Canada, the triad of early
detection of breast cancer was breast self-examination (BSE), clinical breast
exam, and mammography. These three were
the most widely used tools in the early detection of breast cancer.
However, in the late 1990 and early 2000s, breast
self-examination came under attack, and even such organizations as the Canadian
Breast Cancer Foundation modified their recommendations from promoting BSE to
promoting breast awareness “because there is insufficient or inconclusive
scientific evidence of an effective BSE technique, or an effective way for
health care providers to teach it to women, or that BSE reduces breast cancer
mortality.” [1]
Although clinical breast exams (CBE) should be part of a
regular check-up, many health care practitioners have either not been taught
the correct way to perform CBE or do not have the time to include one in a
patient’s annual check-up. In addition, the Ontario Breast Screening Program,
which used to offer a clinical breast exam as well as a mammogram for women
aged 59-70, no longer performs CBEs.
And increasingly,
mammography has been under attack.
The latest in a fairly
long line of studies that criticizes screening mammography is the Canadian
National Breast Cancer Screening Study, “Too Much Mammography,” published on
February 11, 2014 in The British Medical Journal (http://www.bmj.com/content/348/bmj.g1403). This Canadian study followed approximately 90,000
women who were assigned to either receive regular mammograms or have no
mammograms between the years 1980 and 1985. Researchers followed the
participants for about another 25 years.
“During the screening period, approximately 660 invasive
breast cancers were diagnosed in women who received mammograms, and about 520
cases were diagnosed in those who did not receive the screening. Among the
women diagnosed through mammograms, 180 died of breast cancer, and 171 died
from the group who were diagnosed without mammography.
“According to the findings, mammograms contributed to the
over-diagnosis of breast cancer — meaning the screening detected a cancer that
was not an actual threat to the woman’s health, but she still underwent
chemotherapy, surgery, or radiation.”[2]
In her statement on the Canadian National Breast
Screening Study, National Breast Cancer Coalition president Fran Visco says
that the study “confirms NBCC’s long-held position that an enormous amount of
resources and attention have been spent on mammography, despite the lack of
strong evidence that screening significantly reduces mortality from breast
cancer. The Canadian study found that 22% of women whose cancers were detected
by mammograms were overdiagnosed and subjected to unnecessary treatment.”[3]
What’s a woman (or
man) to do now?
Over 24,000 Canadians were diagnosed with breast cancer
in 2013 – 23,800 women and 200 men[4] – so doing nothing
is not an option, and early diagnosis is still important.
Already there are suggestions that we should take another
look at breast self-exams and clinical breast exams.[5] Apparently one
unexpected but positive outcome of the Canadian
National Breast Cancer Screening Study was that “women
who did not receive regular mammograms were instead monitored with physical
breast exams that proved effective. All of the participants were taught to
examine their own breasts once a month, and specially trained nurses examined
women who were in their 50s. This low-tech approach, the researchers found,
appeared to be as good as or better than regular mammograms at locating the
serious cancers that needed treatment.”[6]
Researchers went on to say that they were reluctant to address this, since it
had not been the purpose of the study.
Confusing? Yes. Important?
Undoubtedly. Implications for screening for other cancers? Evidently so: several recent studies have reported on and
described overdiagnosis and overtreatment of not only breast but also prostate and thyroid cancers, and to
a lesser degree renal and lung cancer.[7]
But when it
comes right down to it, existing breast cancer screening methods are still
breast self-examination, clinical breast examination and mammography.
And in fact, in
a February 14, 2014 media release, Dr. Jacques Lévesque, President of the
Canadian Association of Radiologists (CAR), the national association
representing radiologists in Canada, stated that, “Women should continue to
seek breast cancer screening using mammography, a form of x‐ray of the breast.” The CAR
went on to say that they are very concerned that women will feel there is
no need to pursue breast cancer screening, when in fact, several other
breast cancer screening reports indicate the opposite.
The CAR joined the American College of Radiology and the
Society of Breast Imaging, who also have concerns that the report is
“incredibly misleading analysis based on the deeply flawed and widely
discredited Canadian National Breast Screening Study (CNBSS). The results
of this BMJ study, and others resulting from the CNBSS trial, should not
be used to create breast cancer screening policy as this would place a great
many women at increased risk of dying unnecessarily from breast cancer.”[8]
The recently released CAR Practice Guidelines and
Technical Standards for Breast Imaging and Intervention, as well as
referral guidelines for medical imaging for physicians, encourage women to
speak with their physician about the right time to begin mammography
exams.
The Canadian Cancer Survivor Network will continue to
address issues in cancer screening as they arise. We encourage patients,
survivors and caregivers to share their thoughts and opinions about cancer
screening by writing to jmanthorne@ccsn.ca
.
[1]
Look and feel, https://www.cbcf.org/central/AboutBreastHealth/Breast-Awareness/be-breast-aware/Pages/Look-and-Feel.aspx
[2]
Doctors critical of mammography study, NapaValleyRegister.com, February 24,
2014
[3]
National Breast Cancer Coalition Statement on The Canadian National Breast
Screening Study, http://www.breastcancerdeadline2020.org/about-nbcc/newsroom/2014PressReleases/CanadianScreeningStudyStatement.html
[4]
Canadian Cancer Statistics 2013, http://www.cancer.ca/~/media/cancer.ca/CW/cancer%20information/cancer%20101/Canadian%20cancer%20statistics/canadian-cancer-statistics-2013-EN.pdf
[5] A
fresh case for breast exams by Roni Caryn Rabin, The New York Times, http://well.blogs.nytimes.com/2014/02/17/a-fresh-case-for-breast-self-exams/?smid=tw-share
[6]
Ibid
[7]
PubMed, http://www.ncbi.nlm.nih.gov/pubmed/22472510
[8] http://www.acr.org/News‐Publications/News/News‐Articles/2014/ACR/BMJ‐Article‐on‐Breast‐Cancer‐Screening‐
Effectiveness‐Incredibly‐Flawed‐and‐Misleading
