Pilot trial of digital breast tomosynthesis (3D mammography) for population-based screening in BreastScreen Victoria.

Objectives: To estimate detection measures for tomosynthesis and standard mammography; to assess the feasibility of using tomosynthesis in population-based screening for breast cancer.

Design, Setting: Prospective pilot trial comparing tomosynthesis (with synthesised 2D images) and standard mammography screening of women attending Maroondah BreastScreen, a BreastScreen Victoria service in the eastern suburbs of Melbourne.

Participants: Women at least 40 years of age who presented for routine breast screening between 18 August 2017 and 8 November 2018.

Main Outcome Measures: Cancer detection rate (CDR); proportion of screens that led to recall for further assessment.

Results: 5018 tomosynthesis and 5166 standard mammography screens were undertaken in 10 146 women; 508 women (5.0% of screens) opted not to undergo tomosynthesis screening. With tomosynthesis, 49 cancers (40 invasive, 9 in situ) were detected (CDR, 9.8 [95% CI, 7.2-13] per 1000 screens); with standard mammography, 34 cancers (30 invasive, 4 in situ) were detected (CDR, 6.6 [95% CI, 4.6-9.2] per 1000 screens). The estimated difference in CDR was 3.2 more detections (95% CI, -0.32 to 6.8) per 1000 screens with tomosynthesis; the difference was greater for repeat screens and for women aged 60 years or more. The recall rate was greater for tomosynthesis (4.2%; 95% CI, 3.6-4.8%) than standard mammography (3.0%; 95% CI, 2.6-3.5%; estimated difference, 1.2%; 95% CI, 0.46-1.9%). The median screen reading time for tomosynthesis was 67 seconds (interquartile range [IQR] 46-105 seconds); for standard mammography, 16 seconds (IQR, 10-29 seconds).

Conclusions: Breast cancer detection, recall for assessment, and screen reading time were each higher for tomosynthesis than for standard mammography. Our preliminary findings could form the basis of a large scale comparative evaluation of tomosynthesis and standard mammography for breast screening in Australia.

Trial Registration: Australian New Zealand Clinical Trials Registry, ACTRN12617000947303.