WEDNESDAY, June 18, 2014 (HealthDay News) -- Mammography
screening of healthy women reduces deaths from breast cancer by
about 28 percent, according to a new study.
This latest research, published online in the June 18 issue of
BMJ, is likely to reignite the debate over the timing of
breast cancer screening for women at average risk of the
"Mammography screening saves lives -- most likely due to earlier diagnosis of breast cancer -- and therefore better effect of treatment," said study researcher Dr. Lars Vatten, a professor of epidemiology at the Norwegian University of Science and Technology in Trondheim.
Although Vatten calls the benefits of X-ray screening
substantial, two U.S. experts say they're "modest at best."
"While the benefits are small, the harms of screening are real and include overdiagnosis, psychological stress, and exorbitant health care costs," Dr. Joann Elmore of the University of Washington School of Medicine in Seattle and Dr. Russell Harris of the University of North Carolina, Chapel Hill, wrote in an editorial accompanying the study.
Doctors should provide women with balanced information about the
pros and cons of routine mammograms so that they can make informed
decisions, the editorialists said.
But Vatten believes the risks are small compared to the upside
of screening. "The reduction in mortality is large enough to
outweigh the harms related to mammography screening," he said.
Experts are divided about the ideal age for women to begin
having the exam and how often. In 2009, the U.S. Preventive
Services Task Force, an independent panel of experts, recommended
that women ages 50 to 74 get a mammogram every two years. It said
women between 40 and 49 should talk to their doctor about whether
to have the exam every two years. The task force had no
recommendation for women 75 and older.
However, the American Cancer Society and other medical
organizations continue to recommend women at average risk start
annual mammograms at age 40.
In the new study, Vatten and his colleagues evaluated the
effectiveness of mammograms by comparing death rates from breast
cancer among Norwegian women between 1986 and 2009. They looked at
data on women ages 50 to 69 who were invited to get a mammogram
every two years and those who were not yet invited because the
national program was being phased in.
They evaluated more than 15 million person-years of observation,
finding breast cancer deaths occurred in 1,175 of the women invited
for a mammogram, and nearly 9,000 of those who weren't invited for
screening. "Person-years" is a method used by researchers to take
into account the number of people in a study and the amount of time
each was in it.
The 28 percent reduction in breast cancer deaths they found
means that for every 10,000 women invited to get a mammogram, about
27 deaths from breast cancer could be avoided.
The researchers then estimated the effect of the invitation to
get a mammogram among women who actually got one, figuring that
about three-quarters followed through. They estimated a 37 percent
reduction in breast cancer deaths among women who actually got the
Besides evaluating the effect of the mammograms on breast cancer
deaths, "a second aim was to find out how many women need to be
invited to mammography screening to prevent one breast cancer
death," Vatten said. "And we found that 368 women need to be
invited to prevent one death."
Furthermore, 280 women would need to be screened to prevent one
breast cancer death, they estimated.
The benefits found in the Norwegian study reflect the findings
of other studies, said Robert Smith, director of cancer screening
for the American Cancer Society.
Smith, who wasn't involved in the study, said he, too, would
describe the benefits found as substantial.
"This provides strong support for the value of a screening program for breast cancer," Smith said. However, the study wasn't designed to assess when mammograms should begin or how often they should be repeated.
For more on mammograms, visit the
U.S. National Cancer Institute.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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