Digital mammography screening: sensitivity of the programme dependent on breast density

Abstract

Objectives: To analyse the impact of breast density on the sensitivity of a population-based digital mammography screening programme (SP) as key evaluation parameter.

Methods: 25,576 examinations were prospectively stratified from ACR category 1 to 4 for increments of 25 % density during independent double reading. SP was calculated as number of screen-detected cancers divided by the sum of screen-detected plus interval cancers (24-months period) per ACR category, related to the first reading (a), second reading (b) and highest stratification if discrepant (c). Chi-square tests were used for comparison.

Results: Overall sensitivity of the programme was 79.9 %. SP in ACR 4 (a: 50 %, b: 50 %, c: 50 %) was significantly lower than in ACR 3 (a: 72.9 %, b: 79.4 %, c: 80.7 %, p < 0.001), ACR 2 (a: 83.9 %, b: 85.7 %, c: 83.2 %, p < 0.001) and ACR 1 (a: 100 %, b: 88.8 %, c: 100 %; p < 0.001). Frequencies of ACR 4 were a: 5.0 %, b: 4.3 %, c: 6.9 %.

Conclusion: Digital mammography screening with independent double reading leads to a high overall SP. In the small group of women with breast density classified as ACR 4 SP is significantly reduced compared to all other ACR categories.

Key points: • Overall sensitivity of a population-based digital mammography screening programme (SP) was 79.9 %. • In women with ACR 1, 2, or 3, SP ranged between 72.9 %-100 %. • ACR 4 was rare in participants (<7 %) and SP was only 50 %. • SP in ACR 4 differed significantly from ACR 3 (p < 0.001).

Keywords: Breast cancer screening; Breast density; Digital mammography; Interval cancer; Population surveillance.