Background: Most breast screening programs worldwide have replaced screen-film mammography with full-field digital mammography in expectation of technical, clinical and economic advantages. However, we are only now able to measure the effects of this practice shift on health outcomes among asymptomatic women eligible for population screening.
Aim: This systematic review assess the impact of screening with digital mammography on screen detected breast cancer rates and interval cancer rates, as indicators of additional net benefit through early detection, or additional net harm from overdiagnosis.
Methods: We searched Medline, Premedline, PubMed, Embase, NHSEED, DARE and Cochrane databases and identified 2139 potentially eligible papers. 31 papers were included after exclusions for relevance, duplication and other exclusion criteria. Primary outcomes are detection rates and interval cancer rates. Secondary outcomes include recall rates, false positive rates, and positive predictive values. Results are stratified by first and subsequent screening rounds.
Results: Preliminary results for primary outcomes reveal a small increase in screen detected cancers across all studies. In 7 studies with data on interval cancer rates, we observed a statistically non-significant decrease in interval cancer rates.
Conclusion: This pattern of results shows a small increase in cancer detection which may result in future benefit for screened women, but is also consistent with an increase in overdiagnosis. This reinforces the need to carefully evaluate effects of future changes in technology such as 3D mammography to ensure incremental changes to screening programs do not lead to a poorer ratio of benefit to harm from screening.