Breast screening with ultrasound in women with mammography-negative dense breasts: evidence on incremental cancer detection and false positives, and associated cost.

BACKGROUND: We evaluated the contribution of ultrasound (US) in detecting breast cancer in women with dense breasts and negative mammograms.

METHODS: 9157 (35.8%) of 25,572 self-referring women during 2000-2007 had BI-RADS D3-4 negative mammograms - all were screened with bilateral US.

RESULTS: US detected 37 cancers - incremental cancer detection rate (ICDR) was 0.40% (95% CI: 0.39-0.41%); ICDR was 0.33% in women <50 and 0.51% in those 50 years and older. US detected a larger proportion of cancers below age 50 compared to older women. US-only detected cancers had a more favourable stage (pTis-pT1a-pT1b: 64.8% versus 35.5%, p=0.001; pN1: 13.5% versus 31.3%, p=0.047) than cancers detected on mammography. US caused additional investigations in 4.9% of women and benign surgical biopsies in 0.9%. Cost per US-screened woman, and per US-detected cancer ranged between euro59-62 and euro14,618-15,234, respectively.

CONCLUSION: US detects early-stage cancers in women with mammography-negative dense breasts, with higher contribution in women younger than 50 years.