In a new study, researchers found that the shift from film to digital mammography increased the detection of breast cancer by 14% overall in the United Kingdom without increasing the recall rate.
Digital mammography was introduced into clinical use more than 15 years ago and has been widely adopted due to the numerous advantages it has over its predecessor, screen-film mammography.
Image quality with digital mammography is improved over that of screen-film mammography.
In particular, digital mammography provides the ability to visualize calcifications and see through denser tissue, and it allows the reader to adjust the image.
In the study, the team assessed digital mammography’s impact on cancer detection using data from the 80 facilities of the English National Health Service Breast Cancer Screening Program.
The huge trove of data combined with estimates of digital mammography usage enabled the researchers to measure the effect of digital mammography in 11.3 million screening exams in women between the ages of 45 and 70.
The overall cancer detection rate was 14% greater with digital mammography, with substantially higher detection of grade 1 and grade 2 invasive cancers—early-stage cancers that could advance to life-threatening disease if not detected and treated early enough.
At first screening exams for women aged 45 to 52, digital mammography increased the overall detection rate by 19%.
Importantly, the higher sensitivity of digital mammography did not increase the recall rate—the rate at which women are called back for additional screening based on suspicious results.
The team suggests that this improvement happened in the absence of other changes in the English screening program, such as a change in recall rate or the introduction of computer-aided detection.
So they can be clear that the increased rate of detection is due to the change in technology.
Digital mammography increased the detection of some types of cancers more than others.
For instance, digital mammography significantly increased the detection of ductal carcinoma in situ, or DCIS, early-stage cancer confined to the milk ducts of the breast, at both first screens and subsequent screens.
These results confirm that digital mammography is superior to screen film mammography in finding invasive cancers and DCIS.
Women are more likely to have cancer detected with a digital mammogram.
While digital mammography improved detection of grade 1 and 2 cancers, the researchers found no improvement in the detection of grade 3 invasive cancers.
Grade 3 cancers are faster-growing and more likely to spread than grade 1 and 2 cancers.
The team is looking at the radiological features of grade 3 cancers on digital mammography to see if optimizing the image for these lesions, which are often nonspecific and ill-defined soft tissue densities, can aid detection.
They are also studying the relationship between grade 3 cancers and subsequent interval cancers, or cancers that appear between screenings.
One study co-author is Rosalind M. Given-Wilson, M.B.B.S., from St. Georges University Hospitals NHS Foundation Trust in London.
The new study is published in the journal Radiology.
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