Radiology: Digital mammo delivers lower screening recalls

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The deployment of digital mammography can reduce the number of false-positive callbacks in a breast cancer screening program, according to the results of a retrospective study conducted in Barcelona, Spain, and published in the July issue of Radiology.

“The false-positive recall rate is one of the adverse effects of a screening program, leading to additional tests—some of which are invasive, increasing costs, and provocation of anxiety in women before malignancy is ruled out,” the authors wrote. “Reducing the false-positive rate could prevent a large number of women from experiencing the consequences of this adverse effect.”

Researchers performed an analysis of data from two screening rounds of a breast cancer screening program, one round using screen-film mammography (12,958 women) and one round using digital mammography (6,074 women).

All mammograms from both groups were read by the same team of radiologists with the same experience in reading, double reading was always performed, and previous mammograms were available in successive screening rounds but not in the first screening round.

The results demonstrated that recall rates and the rates of invasive tests performed were lower in the digital mammography group (4.2 percent) than in the screen-film mammography group (5.5 percent), whereas no significant differences between the groups were observed for the overall cancer detection rate.

However, the cancer detection rate was higher, 10.7 percent, in the first screening round in the digital mammography group. The authors noted that the proportion of menopausal women was lower in the first screening round than in successive screening rounds, which could partly explain the higher cancer detection rate for digital mammography in this group

In addition, the percentage of core biopsy was higher in the digital mammography group than it was in the screen-film mammography group in the first screening round. The authors suggested that one reason for this finding could be that digital mammography allows image processing, such as edge enhancement and contrast resolution to be modified, enhancing the visibility of calcifications, which are examined with core biopsy.

The researchers noted that their objective was to evaluate the effect of the introduction of digital mammography technology in the context of a population-based screening program. As such, a limitation of the study was that it was not random. In addition, the study population was limited to the relatively short period since the introduction of digital technology into the program and the selection of comparable groups.