UPDATE 1-Study leaves US women with conflicting advice on mammograms

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CHICAGO, Nov 27 (Reuters) - Controversial U.S. guidelines

for mammography issued in 2009, calling for screening every two

years rather than annually for women over 50 years old, can

result in breast cancers being missed, according to U.S.

researchers studying the hotly debated topic.

This latest study assessing the impact of revised guidelines

issued by the U.S. Preventive Services Task Force three years

ago comes on the back of a chilling analysis published last week

in the New England Journal of Medicine (NEJM).

The NEJM study, using three decades of U.S. government data,

found that nearly one in three patients - or 1.3 million women -

whose cancer was detected through routine mammograms was treated

for a tumor that may not have been life threatening.

Routine screening has traditionally been recommended by the

task force and the American Cancer Society for all women over

the age of 40. The American Cancer Society has not changed its

stance, but the task force issued new guidelines in 2009,

recommending mammography every two years for women 50 to 74

years old.

Dr. Elizabeth Arleo of Weill Medical College of Cornell

University and lead researcher examined the impact of the

revised task force guidelines on women ages 40 to 49, and 65

years and older.

Arleo analyzed data on screening mammography at New York

Presbyterian Hospital/Weill Cornell Medical Center between 2007

and 2010. Over those four years, 43,351 mammograms were

performed, leading to the detection of 205 breast cancers.

Nearly 20 percent of cancers detected with screening mammography

were found in women in their 40s.

"In our book, it seems unacceptable to miss 19 percent of

breast cancers, half of which were invasive," she said, noting

that "invasive" cancers are more advanced because they reside in

the breast tissues and not just the milk ducts, considered to be

the earliest form of breast cancer.

"Our findings favor the American Cancer Society

recommendations. Women over 40 should have annual mammograms. In

my book, there's no confusion. I tell my patients, I tell my

friends and I tell my mother to get annual mammograms," Arleo

said in a telephone interview. "We hope we can quell some of the

confusion."

Arleo pointed out that not one of the 16 members of the U.S.

Preventive Services Task Force is a breast surgeon or breast

imager.

Arleo, who presented her findings at the Radiological

Society of North America meeting in Chicago, dismissed the NEJM

analysis, calling the premise, methods and conclusions of the

analysis flawed.

The NEJM study, she said, is predicated on the theoretical

idea that all women get screened, but in reality, only about

one-third of women over 65 years old actually get screened.

The method is flawed because researchers combined data from

women with breast cancer in the milk ducts with those who had

small invasive cancers, thereby falsely diminishing the results

for late-stage cancers.

And the conclusion is flawed because no one can say for sure

which cancers would have progressed to an advanced or

life-threatening state.

"We need to understand the biology of cancer so we know

which cancers to treat. Until that question is answered,

screening is our best shot," she said.

She acknowledged that false positives are a problem of

widespread screening.

"But for every test, you have to do a risk-benefit analysis,

not just for mammography," Arleo added.

(Reporting by Debra Sherman; Editing by Lisa Shumaker and

Maureen Bavdek)

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