Should tailored screening with additional digital breast tomosynthesis vs. no additional digital breast tomosynthesis be used in organised screening programmes for early detection of breast cancer in asymptomatic women with high mammographic breast density detected for the first time with digital mammography in screening?

The majority of the GDG agreed that the balance of desirable and undesirable effects probably favours the addition of DBT. The overall certainty in the evidence is very low because of uncertainty in the estimates for interval breast cancers, false positives and invasive breast cancers, and the absence of data for the downstream impact on breast cancer mortality.

The evidence shows that with the addition of DBT, there are more breast cancers detected. In addition, there may be more invasive breast cancers detected, although the proportion to non-invasive ductal carcinoma (DCIS) which are clinically less relevant cancers, is unknown. Adding DBT may have little to no effect on interval breast cancers, but this evidence is very uncertain. Overall, the moderate desirable effects of adding DBT probably outweigh the small increase in false positives.

There are moderate costs associated with DBT over DM, which could increase health inequities if implemented, but there are fewer women with high breast density in the target population for screening. Implementation of DBT would be facilitated by increased availability of DBT machines, adequate human resources (radiologists and technical personnel), and financial resources.

The majority of the GDG agreed with the recommendation: 8 members voted for a conditional recommendation for the addition of DBT, 3 members voted for a conditional recommendation for either adding or not adding DBT, 1 member voted for a conditional recommendation against adding DBT, and 1 member abstained.

• Feasibility and acceptability could be assessed in the monitoring of programmes.
• Quality control procedures and quality standards should be further developed. Standards should be developed in particular for the image quality of synthesised 2D images from the tomosynthesis technology.

• There is a need for research examining the classification of mammographic breast density and standardisation of the classification systems used for breast density, including technology for the automation of determing breast density. Research should also aim at establishing the appropriate density threshold for additional imaging.
• An optimal combination of screening modalities in women with high breast density should be conducted in the research setting.
• Additional research on the subgroups who could possibly benefit from DBT (not only for women with high density but also for other potential risk factors e.g., age groups for risk stratification).
• Additional trials providing further evidence on second round breast cancer detections, including information on the downstream consequences.