Abstract P6-02-05: Digital versus screen-film mammography in population-based breast cancer screening: Performance indicators and tumor characteristics of screen-detected and interval cancers
Authors: De Munck L , De Bock GH , Otter R , Reiding D , Broeders MJM , Willemse PHB , Siesling S 
Published: May 2016

Abstract
Purpose:
To evaluate whether the introduction of full-field digital mammography (FFDM) in screening has resulted in any changes in performance indicators compared to screen-film mammography (SFM), including tumor characteristics and incidence rates of interval cancers.
Materials and Methods
Data of the Dutch National Cancer Screening Programme, region North (2004-2010) were linked to the Netherlands Cancer Registry (N=902,868). Screening performance indicators (recall rate, detection rate, positive predictive value, sensitivity and specificity) and tumor characteristics of screen-detected cancers were compared between FFDM and SFM, as were incidence rates and tumor characteristics of interval cancers. Analyses were stratified by initial and subsequent examinations. Differences were compared using chi-square.
Results
Initial examinations: After initial examinations recall rates were 2.1% for SFM and 3.0% for FFDM (p&lt;0.001). The positive predictive value was 25.6% for SFM and 19.9% for FFDM (p=0.002) and detection rates were similar. The detection rate for DCIS was 0.86 per 1000 women for SFM compared to 1.18 per 1000 women for FFDM (p=0.137). Similar percentages of low grade DCIS were found for SFM and FFDM (18% vs. 14%;p=0.860). No difference were found in tumor size, morphology, grade and nodal status of invasive screen-detected cancers.
Subsequent examinations: After subsequent examinations performance indicators were similar. Detection rates for DCIS were 0.74 per 1000 women for SFM versus 0.81 per 1000 women for FFDM (p=0.298). For invasive cancers, detection rates were 4.54 per 1000 women for SFM versus 4.33 per 1000 women for FFDM (p=0.210). The percentages of low grade DCIS were similar for SFM and FFDM (12% vs.9%; p=0.524). Invasive cancers diagnosed with FFDM were more often of high grade (p=0.024) and ductal type (p=0.030).
No difference was found in the incidence rates of interval cancers for SFM and FFDM after initial examinations (2.69/1000 vs.2.51/1000; p=0.787). The sensitivity after initial examinations was 66.1% for SFM and 69.1% for FFDM (p=0.657), specificity was 98.5% and 96.9% for SFM and FFDM, respectively (p&lt;0.001). After subsequent examinations the incidence rates of interval cancer were 2.30/1000 for SFM and 2.41/1000 for FFDM (p=0.652), sensitivity was 69.7% for SFM and 66.7% for FFDM (p=0.232). Specificity was 99.4% SFM and 99.2% for FFDM (p&lt;0.001). No differences were found in tumor size, morphology, grade or nodal status of interval cancers diagnosed after FFDM compared to SFM after initial or after subsequent examinations.
Conclusions
Compared to SFM, FFDM resulted in similar rates of screen-detected and interval cancers, indicating that FFDM performs as well as SFM in a breast cancer screening program, with more invasive cancers of high grade and ductal type found after subsequent screens. FFDM resulted in a higher recall rate and lower PPV. No signs of an increase in low-grade DCIS (which might connote possible overdiagnosis) were seen. Tumor characteristics of interval cancers were similar.
Citation Format: De Munck L, De Bock GH, Otter R, Reiding D, Broeders MJM, Willemse PHB, Siesling S. Digital versus screen-film mammography in population-based breast cancer screening: Performance indicators and tumor characteristics of screen-detected and interval cancers. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-02-05.