Evidence of the effect of adjunct ultrasound screening in women with mammography-negative dense breasts: interval breast cancers at 1 year follow-up.

Surveillance of interval cancers (IC) provides a measure of breast screening efficacy. Increased breast density is a predictor of breast cancer risk and of the risk of IC in screening. Improving screening sensitivity in women with dense breasts, through adjunct ultrasound (US), may potentially reduce IC; however this has not been proven. We report on first-year IC in a retrospective cohort of 8865 women who had 19,728 screening examinations (2001-2006): women with non-dense (D1-D2) breasts received mammography (M) screening, and women with dense (D3-D4) breasts also received ultrasound. Data linkage with both hospital discharge records and cancer registry databases was used to identify IC. Underlying cancer rates (cancers observed within 1-year from screening) were 6.3/1000 screens in the D1-D2 group and 8.3/1000 screens in the D3-D4 group. Cancer detection rate (CDR) was 5.98/1000 in all screening examinations; in D3-D4 breasts ultrasound had an additional CDR of 4.4/1000 screens. There were 21 first-year IC, an overall interval cancer rate (ICR) of 1.07/1000 negative screens: 0.95/1000 in women < 50 years and 1.16/1000 screens in women ≥ 50 years. ICR by breast density were 1.0/1000 negative screens in D1-D2, and 1.1/1000 negative screens in D3-D4. Interval cancers were early stage (in situ or small invasive) cancers, almost all were node-negative. Screening sensitivity was 83.5% for mammography alone in D1-D2 breasts relative to 86.7% for mammography with ultrasound in D3-D4 breasts. Our study shows that including ultrasound as adjunct screening in women with D3-D4 breasts brings the IC rate to similar levels as IC in non-dense breasts--this suggests that additional cancer detection by ultrasound is likely to improve screening benefit in dense breasts, and supports the implementation of a randomised trial of adjunct ultrasound in women with increased breast tissue density.

[Interval cancers as indicators of performance in screening programmes]. / I carcinomi di intervallo quali indicatori di performance di un programma di screening.

GISMa analyses the interval cancer (IS) topic providing guidelines and reference standards in addition to CE recommendations. IC identification is based on Cancer Registries (CR), if existing, or on hospital discharge records, in alternative. The optimal measure of IC frequency (inversely correlated with sensitivity) is the IC proportional incidence (observed IC/carcinomas expected in absence of screening). Other formulas (IC/IC + screen detected cancers; IC rate per 1000 negative screens) look less reliable. IC stage at diagnosis (if available through CR) must be compared with screen detected cancer and cancer detected in non-attenders. Review of mammograms preceding the IC (coded as screening error, minimal signs, or occult) should be done mainly with a blind procedure (IC mixed with negative controls), as this procedure is more representative of the original scenario and more respectful of radiologist's rights.

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.