(Refiles to delete extraneous words at start of hedline)
* No greater risk seen even in women on hormones or with
* American Cancer Society considering change in screening
* Women in their 40s with dense breasts may need annual
By Julie Steenhuysen
CHICAGO, March 18 In the latest installment in
the mammogram debate, a new study finds that getting a mammogram
every other year instead of annually did not increase the risk
of advanced breast cancer in women aged 50 to 74, even in women
who use hormone therapy or have dense breasts, factors that
increase a woman's cancer risk.
The findings, released on Monday by researchers at the
University California, San Francisco, support the conclusions of
the U.S. Preventive Services Task Force, an influential
government panel of health advisers, which in 2009 issued
guidelines that said women should have mammograms every other
year starting at age 50 rather than annual tests starting at age
The controversial recommendations to reduce the frequency
and delay the start of mammogram screening were based on studies
suggesting the benefits of detecting cancers earlier did not
outweigh the risk of false positive results, which needlessly
expose women to the anguish of a breast cancer diagnosis and the
ordeal of treatment.
The matter, however, is not settled. The American Cancer
Society still recommends women be screened for breast cancer
every year they are in good health starting at age 40, but the
group is closely watching studies such as this.
"I don't think any one study ought to change everything,"
Dr. Otis Brawley, chief medical officer of the American Cancer
Society, said in a telephone interview. But he added, "This is
one of several studies that are all pointing in the same
direction over the last several years."
Brawley said he did not expect screening recommendations
from professional organizations to change in the next year, but
he does see doctors moving toward a more personalized approach
over the next five years. There may be some women who need to be
screened every six months and others every two years depending
on their breast density, family history and genetic testing.
In the latest study, Dr. Karla Kerlikowske of the University
of California, San Francisco, and colleagues wanted to see
whether risk factors beyond a woman's age play a role in the
decision of when to start mammogram screening.
In addition to age, the team considered whether women had
dense breast tissue - which has a higher ratio of connective
tissue to fat - or took combination estrogen and progesterone
hormone therapy for more than five years, both of which can
increase the risk of breast cancer.
"If you have these risk factors, would it help if you got
screened annually vs. every two years?" said Kerlikowske, whose
study was published online in JAMA Internal Medicine.
To study this, the team analyzed data from 11,474 women with
breast cancer and 922,624 without breast cancer gathered from
1994 to 2008. Even after looking at these other factors, the
team found no increased risk of advanced cancer in women 50 to
74 who got a mammogram every other year instead of every year.
"It didn't matter whether you screened that group every year
or every two years, the risk of advanced disease or having a
worse tumor was no different," Kerlikowske said.
More frequent screening in these women did result in more
false-positive results. Women aged 50 to 74 who had annual
mammograms had a 50 percent risk of having a false-positive
result over a 10-year period, but a 31 percent risk when they
were screened every other year.
Studies suggest a false positive can have lasting
psychological effects. A March study in the Annals of Family
Medicine said, "Three years after a false-positive nding, women
experience psychosocial consequences that range between those
experienced by women with a normal mammogram and those with a
diagnosis of breast cancer."
Breast density was a factor in younger women, however.
When the team looked at screening frequency in women 40 to 49,
they found those with extremely dense breasts who were screened
every other year had a higher risk of having a more advanced
cancer than those who got screened every year. Younger women
also were far more likely to have false-positive results and
undergo unnecessary procedures.
Without getting a mammogram in their 40s, Kerlikowske said,
"women aren't going to know if they have extremely dense
Among women in their 40s, about 12 percent to 15 percent
have extremely dense breast tissue. For these women, Kerlikowske
said she recommends that they get a mammogram if they have other
risk factors that might put her at risk of breast cancer,
including having a first-degree relative that a common term, or
just "close relative"? such as a mother or a sister with breast
"Once we see their breast density is high, we will offer
annual mammography," she said.
The American College of Radiology and the Society of Breast
Imaging, groups that represent radiologists, said the study's
methodology was flawed because it used early and late breast
cancers to determine the outcomes of breast screening rather
than more refined measures of tumor size, nodal status and
cancer stage, which could determine whether screening detected
cancers at an earlier stage.
It also faulted the study for not being a closely
controlled, randomized clinical trial. The study used data from
the Breast Cancer Surveillance Consortium, a national
mammography screening database that gathers information from
community mammography clinics on millions of women.
"We're never going to have a randomized study. This is the
best in terms of the type of study anyone can actually hope
for," said Brawley, whose group monitors scores of breast
studies from around the world each year. He said such a study
would take decades and would be prohibitively expensive.
Catching cancers earlier does not always translate into
lives saved, according to a November study published in the New
England Journal of Medicine by Dr. Gilbert Welch of the
Dartmouth Institute for Health Policy & Clinical Practice in New
That study suggested that as many as a third of cancers
detected through routine mammograms may not be life-threatening,
contradicting the deeply ingrained belief that cancer screening
is always good.
Kerlikowske said the strength of her study is that it allows
researchers to consider other risk factors, such as breast
density, allowing doctors to offer women personalized choices
about when to start breast cancer screening.
"We're trying to move it away from this idea that it all
should be based on age. There should be some thoughtfulness to
it," she said.
(Reporting by Julie Steenhuysen; Additional reporting by Bill
Berkrot; Editing by Jilian Mincer and Douglas Royalty)