Digital versus screen film mammography: Impact on positive predictive values following transition.

12 Background: The Calgary Health Region changed from screen film mammography (SFM) to digital mammography (DM) in 2005. This retrospective study was designed to determine the effect of this conversion on positive predictive values (PPV) for cancerous and precancerous breast lesions. Methods: In the Calgary region, biopsies for mammographic calcifications are only done at Foothills Medical Centre (FMC) by a small group of mammographers employing homogeneous techniques. From FMC’s database, we reviewed core biopsy data for mammographic calcifications in the years 2002-2004 (SFM years) and 2008-2010 (DM years). Mammographic masses were excluded. We determined PPVs for each set of years for detection of cancerous lesions (PPV3for calcifications). We further calculated the PPVs of SFM and DM for detection of high-risk lesions, including ADH, ALH, LCIS, and papilloma collectively (precancerous lesions). The detection rates of benign lesions (excluding precancerous lesions) after biopsy were also determined. St...