Missed Breast Lesions Found After the Fact
She says, too, the fact that about half the lesions were found in fatty breasts suggests that sometimes mammographers may "let down our guard a little when we have a fatty breast, so that's a teaching point." Traditionally, fatty breasts are easier to detect breast cancers in than are the denser breast tissues.
A remedy for the situation might be having two people review mammograms, and Birdwell says that several institutions do attempt this "second read" approach. "But this has pitfalls too, not the least of which is legal. Who is responsible for dictating the notes? Who signs off on the case? If the first reader is [deemed] responsible, will the second reader be attentive enough?" she says.
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 breasts.
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.