Digital mammography: its impact on recall rates and cancer detection rates in a small community-based radiology...

The purpose of our study was to retrospectively evaluate the impact on recall rates and cancer detection when converting from film-screen to digital mammography in a small community-based radiology practice.

Audits of our institution's records were compiled during a 4-year period: the year before conversion to digital mammography, and the first, second, and third years after conversion. We found that 4,838 film-screenings were performed during the period of audit 1 without the use of the digital system; 6,875 screenings were performed using the digital system during audit 2; 7,379 screenings during audit 3; and 7,294 during audit 4. Cancer detection and recall rates for each of the audits were determined retrospectively. Results were compared between audits using the chi-square test.

Cancer detection rates increased from 4.1/1,000 during film-screenings to 7.9/1,000 (p = 0.01) the year after the introduction of digital mammography. Recall rates also increased the year after digital mammography was introduced, from 6.1% to 10.2% (p < 0.001). Audit 3 showed no statistically significant difference in cancer detection rates from those in audit 1, decreasing to 5.1/1,000 (p = 0.42). However, audit 4 noted an increase in the cancer detection rate to 6.9/1,000.

In this community-based mammography practice, an increase in the cancer detection rate occurred initially during the conversion from film-screen to digital mammography, which subsequently decreased but remained higher than before digital conversion. This study suggests that the new technology alone is responsible for the increased number of cancers detected in patients with dense breasts that were not previously found using film-screening.