Traditionally, mammograms
were considered the best way to find breast cancer on an early stage, when it
is easier to treat. However, lately, the numerous scientific studies
question the standard approach and its application framework, calling for
urgent guidelines revision.
Guidelines
The U.S. Preventative Services Task Force, an expert group
that reviews the latest research findings, recommends that mammography
screening for most women start at age 50 rather than 40, and that the frequency
be every two years (instead of annually) through the age of 74.
The Task Force is widely used as a gold standard for
determining medical treatment and screening.
In this case, they recommended raising the age to 50 more than two years
after the American College of Physicians recommended the same thing, and they
also recommended that women continue to undergo mammograms until age 74 instead
of stopping at 69. The American Cancer
Society strongly disagrees and is still recommending annual mammograms for
women over 40.
The American Cancer Society also recommends regular breast
MRIs in addition to mammograms for women over 40 at high risk for breast
cancer, and as a possible follow-up for abnormalities found by mammogram. Experts do not recommend MRIs for screening
women of average risk, but clinical studies are being done to determine whether
they should be.
New American Study
The new scientific findings recommend doctors to focus on
life expectancy when deciding whether to recommend mammograms for their older
female patients, since the harms of screening most likely to outweigh the
benefits unless women are expected to live at least another decade, according
to a review of the scientific literature by experts at UCSF and Harvard medical
schools.
Accepted national guidelines recommend that doctors make
individualized screening recommendations for all women, including the most adult
group of 75 and older. But the recent investigation concluded that since this
age group has never been included in any mammography trials before, there is yet
to find conclusive evidence that anti breast cancer screening may help them to
live longer and healthier lives.
The researchers concluded that many women in this age group
receive regular mammograms anyway, with no discussion about the uncertain
benefit or potential harms of continued testing, which include unnecessary
treatment for slow-growing cancers or pre-cancerous lesions that pose no real
threat to the women's lives.
They validated that women who are expected to live a decade
or more should talk with their doctors and weigh the potential benefits of
diagnosing a dangerous but treatable cancer through mammography against the
possibility of being misdiagnosed or treated aggressively for a cancer that
posed no real harm.
"People should be informed that everything we do in
medicine can have good and bad effects, and that goes for mammography,"
said Louise Walter, MD, UCSF professor of medicine and chief of the Division of
Geriatrics.
The study authors arrived at their unconventional conclusions
after examining all the studies conducted from 1990 to 2014 that identified
risk factors for late-life breast cancer in women 65 and older, as well as the
studies that assessed the value of mammography for women 75 and older.
Since there were no randomized trials of the benefits of
screening women over 74, they could not say whether mammography was beneficial
for those women. Longitudinal studies found that healthy older women who were
screened with mammography were less likely to die from breast cancer, but
screening was not beneficial for women with serious medical problems.
Modeling studies indicate mammograms would prevent two
cancer deaths for every 1,000 women in their 70s who were screened every two
years for 10 years. However, these studies also predicted that about 200 of
those women would receive test results indicating they had cancer when they did
not, and about 13 would be treated for cancers that posed no harm.
Doctors use complex algorithms to assess breast cancer risk,
but these calculations lose their ability to predict disease in the oldest
women, because risk factors change as women age.
For example, how old a woman was when she first got her
period and whether she bore children and at what age are important factors in
determining breast cancer risk for women under 75. But these factors are no
longer relevant once women reach the age of 75. Instead, the main risk factor
for developing breast cancer is age itself.
"The things that may be predictive in older women
likely have to do with recent hormone exposure, such as lifelong obesity, high
bone density or taking hormones, which are associated with higher estrogen
levels," said Mara Schonberg, MD, MPH, an assistant professor of medicine
at Harvard Medical School. "Distant hormone exposures, such as the age a
woman first got her period, may not make much difference in who gets breast
cancer in this older population. Older age is the greatest risk factor for
breast cancer."
New Canadian Study
Canadian researchers looked at data from the Canadian
National Breast Screening Study, which recruited 89,835 women who were 40-59 at
the beginning of the study, gave each of them a clinical breast exam, then assigned
each participant to one of two groups: a group that would receive annual
mammograms and clinical breast exams for the next four years, or a group that
would receive only annual clinical breast exams for the next four years (or, in
the case of the women 40-49, would just remain under the care of their regular
doctors). Researchers then continued to follow up with the participants until
25 years after their original recruitment.
During the initial screening period, a total of 1,190 breast
cancers were diagnosed (666 in the mammography group, and 524 in the control
group). The tumors detected by mammograms did tend to be slightly smaller and
were a little less likely to be node positive (meaning they had cancerous cells
in them). But the mortality rate didn’t differ much between the two groups:
During the 25-year follow-up period, 180 women in the mammogram group died,
compared to 171 women in the control group.
If you look at the entire study period, 3,250 women in the
mammogram group and 3,133 in the control group were diagnosed with breast
cancer. The number who died were, again, virtually identical: 500 women in the
mammogram group, compared to 505 in the control group.
What’s more, the study authors are asserting that about one
in five of the breast cancer diagnoses made as a result of mammograms were
over-diagnoses. In other words, had these tumors not been detected, researchers
say they never would have caused health issues or required treatment.
“Early detection could be of greater benefit in communities
where most cancers that present clinically are larger and a higher proportion
are node positive,” write the researchers. “However, in technically advanced
countries, our results support the views of some commentators that the
rationale for screening by mammography should be urgently reassessed by policy
makers.”
Self-Examination
While the mammography effectiveness is under heavy debates,
performing your breasts self-examination may be quite benefiting and
comforting. The better you know your body, the more likely you may notice
if something is out-of-the-ordinary and potentially dangerous.
Take charge of your health and learn how to do a breast
self-exam by watching this video.
Dr. Schwartz, M.D., a leading advocate of disease prevention
and wellness for women, confirms that self-examinations are the best way for
women to check for signs of breast cancer.
"We must assume responsibility for our every-day
care," she said. "Women should learn to know and love their breasts
and perform self-examination on a regular basis. They should follow an
anti-inflammatory diet, exercise, and take bio-identical hormones to reduce the
risk of cancer."
If a woman does find a suspicious lump in her breast, Dr.
Schwartz would then suggest testing for cancer, preferably in the form of an
ultrasound, which has less radiation.
Review Risk Factors
When discussing with your doctor whether and how often to have mammograms, take into account your breast cancer risks, which include:
1. Your age. Most aggressive breast cancers are found in
women 55 or older.
2. Your genes. Up to 10 percent of breast cancers are
inherited, most commonly from mutations in the BRCA1 and BRCA2 genes.
3. Your family history. Having a mother, sister, or daughter
with breast cancer increases your risk.
4. Your cancer history. If you've had cancer in one breast,
you're three to four times more likely to develop it again in the same or the
other breast.
5. Your breast density. Women with denser breasts are more
likely to get breast cancer, and their cancer may be harder to spot on a
mammogram.
6. Your use of hormone therapy. Taking combined hormone
therapy after menopause increases breast cancer risk.
Sources and Additional
Information:
http://www.stopcancerfund.org/p-breast-cancer/2012-update-when-should-women-start-regular-mammograms-40-50-and-how-often-is-regular/
