US study finds that three-dimension mammograms detect cancer better
US study shows the technology reduces the number of women needing re-examination
Adding three-dimensional mammography to conventional digital inspection substantially improved detection of invasive breast cancers and reduced the number of women called back for re-examination, according to the first large study of the technology.
Doctors in 13 academic and community health settings discovered 41 per cent more of the most lethal cancers when women had both traditional digital mammograms and the 3D screening known as "tomosynthesis".
The technology, approved by the United States Food and Drug Administration in 2011, provides images that appear as slices of the breast, removing the effect of overlapping breast tissue that can obscure views of tumours.
Sarah Friedewald, co-medical director of the breast unit at Advocate Lutheran General Hospital in Illinois, who led the study released on Tuesday, unequivocally endorsed the value of 3D mammography over conventional imaging.
"In my opinion," she said of any woman about to be screened for breast cancer, "she should have the 3D mammogram."
The paper, published online in the Journal of the American Medical Association, reviewed 454,850 examinations from 13 sites across the country, 281,187 conducted with digital mammography and 173,663 that provided the traditional mammogram and tomosynthesis. The improved technology found 41 per cent more invasive cancers (4.1 per thousand women screened versus 2.9 per thousand) and more cancers overall.
The addition of tomosynthesis also reduced the need to recall women for further testing for false-positive findings.
The 3D screening subjected women to more radiation than traditional mammography, but the amount was still well within limits, Friedewald said. It costs more, was not available everywhere and was not always covered by insurance, she said.
The research did not examine how the patients screened actually fared, which was an area that Friedewald said needed more study.
Breast cancer killed 40,000 women annually, according to the American Cancer Society, although screening mammography has been important in reducing the mortality rate.
In recent years, influential medical boards in the United States, Canada and Switzerland have revised their recommendations on screening mammography as debate continued over false-positive findings and over-diagnosis.
In an editorial that accompanied the 3D study, two doctors who were not involved in the research said the results would renew debate, this time over whether tomosynthesis should replace digital mammography. They called for more research.