Missed Breast Lesions Found After the Fact
While Birdwell reported on cancers that should have been spotted on the
first mammogram, her colleague Debra M. Ikeda, associate professor of radiology
at Stanford, reported on another subset of this study: 174 mammograms that had
"subtle findings but that would not have been selected for recall by most
members of the expert panel."
Ikeda says that "70% of these cancers looked normal." Birdwell says
that it is unclear if any of these cancers could have been identified using any
other technology. She says, for example, that most persons who advocate the use
of ultrasound say that the ultrasound approach should be used in women with
dense breasts. In the cases she and Ikeda presented, half of the women would
not have been selected for ultrasound screening because they don't have dense
While Birdwell says the findings suggest that mammography is far from
foolproof, she adds that the good news is that all of these women did
eventually have their cancers detected by screening mammography and even
invasive cancers were at a very early stage and very treatable.
- Although it is difficult for radiologists to find cancerous lesions in
dense breast tissue, half of all missed lesions occurred in non-dense, or
fatty, breast tissue.
- There was nothing unusual about the types of lesions that were missed,
leading one researcher to suggest that mammographers were just distracted in
the screening room.
- Some institutions have two reviewers read each mammogram, but this
introduces legal issues, such as which person will have the ultimate
responsibility in the reading of the film.