In a new study, researchers found that when MRI was used in between mammography appointments, the women in the study were half as likely to be diagnosed with interval cancer.
That’s cancer that occurs between mammography screenings.
However, MRI screening also resulted in a higher rate of false-positive results compared to mammography.
The research was conducted by a team at the University Medical Center Utrecht in the Netherlands.
About 10% to 20% of women have extremely dense breasts. It’s been known that mammography isn’t as good at finding breast cancers in extremely dense breast tissue.
But what hasn’t been clear is if MRI screening might spot cancers that mammography didn’t.
In the study, the team examined more than 40,000 women in the Netherlands. The women were between 50 and 75 years old. All had extremely dense breast tissue.
They all had a normal mammography screening. A little more than 8,000 were invited to also have an MRI screening in the year between their mammographies.
The researchers found the interval cancer screening rate was 2.5 per 1,000 screenings in the MRI group compared to 5 per 1,000 in the mammography-only group.
The false-positive rate for MRI was nearly 80 per 1,000 screenings. In a previous Dutch study, the false positive rate for mammography was 24 per 1,000 screenings.
The team says the benefits of MRI screening need to be carefully weighed against the harms, as MRI examination is more expensive, and it requires the injection of a contrast agent into the body.
MRI will also detect abnormalities that later turn out not to be breast cancer after all.
Also, MRI may detect breast cancers that grow so slowly that they would never have caused health problems and therefore are treated unnecessarily.
The lead author of the study is Carla van Gils, a professor of clinical epidemiology of cancer.
The study is published in the New England Journal of Medicine.
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