What percentage of women undergoing three-dimensional mammography (digital breast tomosynthesis) and three-dimensional breast ultrasound have abnormal findings requiring additional evaluation?

Abnormal Findings Rate with 3D Mammography and 3D Breast Ultrasound

When combining 3D mammography (digital breast tomosynthesis/DBT) with 3D breast ultrasound screening, approximately 18-24% of women will have abnormal findings requiring additional evaluation, though the specific rate varies by breast density and risk category.

Recall Rates for 3D Mammography (DBT)

The recall rate (abnormal findings requiring additional workup) for DBT screening ranges from 3.6 to 10.3 per 1,000 women screened (0.36-1.03%), which represents a significant reduction compared to 2D mammography alone 1.

• In the Oslo Tomosynthesis Screening Trial, DBT reduced recall rates from 6.7/1,000 to 3.6/1,000 1
• A single-center program reported an 18.8% reduction in recall rates with DBT 1
• Large-scale U.S. screening data showed DBT recall rates of 8.9% compared to 10.3% for 2D mammography 2
• Population-based screening in Italy demonstrated recall rates of 3.4% for DBT with synthetic 2D 3

Abnormal Interpretation Rates When Adding Ultrasound to DBT

The addition of supplemental breast ultrasound to DBT dramatically increases the abnormal interpretation rate:

• DBT alone: 7.8% abnormal interpretation rate 4
• DBT combined with ultrasound: 24% abnormal interpretation rate 4
• Among women with negative DBT findings who then underwent supplemental ultrasound, an additional 18% had abnormal ultrasound findings requiring workup 4

This represents a substantial increase in callbacks when ultrasound is added to DBT screening 4.

Stratification by Breast Density

The benefit and abnormal finding rates vary significantly by breast density 1:

Women with Nondense Breasts:

• Supplemental ultrasound after negative mammography adds 0/1,000 additional cancer detection in nondense breasts 1
• The probability of mammographic failure is only 1% in low-risk women with low breast density 1

Women with Dense Breasts:

• Supplemental ultrasound increases cancer detection by 2.4-3.3 per 1,000 screened 1
• The probability of mammographic failure rises to 40% in high-risk women with dense breasts 1
• All three additional cancers detected by ultrasound after negative DBT occurred in women with dense breasts 4

Cancer Detection Rates

While abnormal findings increase with combined screening, actual cancer detection rates remain relatively low 1, 5:

• DBT cancer detection rate: 4.5-9.4 per 1,000 screens 5, 2, 3
• Additional cancers from supplemental ultrasound: 0.7-3.2 per 1,000 screens after negative DBT 4
• Combined DBT + ultrasound: 12 per 1,000 screens 4

Positive Predictive Value Considerations

A critical caveat: The increased abnormal findings from adding ultrasound come with decreased positive predictive value 1:

• DBT alone: PPV of recall 5.9% 2
• Mammography + ultrasound: PPV of recall decreases to 9.5% compared to 21.4% for mammography alone 1
• This means the vast majority of abnormal ultrasound findings are false positives requiring additional imaging or biopsy 1

Biopsy Rates

The biopsy rate also increases with combined screening 4, 2:

• DBT screening: 14.5-17.6 biopsies per 1,000 screens 2
• Mammography + ultrasound: 52.0 biopsies per 1,000 screens 1
• However, DBT results in fewer surgical excision biopsies (3.2% vs 5.8% for 2D mammography) 6

Clinical Bottom Line

For the average-risk woman with nondense breasts, supplemental ultrasound after DBT provides minimal benefit and substantially increases false-positive callbacks 1, 4. For women with dense breasts, the 18-24% abnormal interpretation rate must be weighed against the additional 2-3 cancers detected per 1,000 women screened 1, 4.