Among women with dense breasts undergoing screening, abbreviated breast magnetic resonance imaging (MRI), compared with digital breast tomosynthesis, was associated with a significantly higher rate of invasive breast cancer detection. No invasive cancer was identified by digital breast tomosynthesis alone or as interval cancer during follow-up. Findings from a cross-sectional study with longitudinal follow-up that included 1444 women who underwent both abbreviated breast MRI and digital breast tomosynthesis are published on 25 February 2020 in JAMA.
Breast density on mammography is a well-documented risk factor for a future breast cancer diagnosis. Improved screening methods for women with dense breasts are needed because of their increased risk of breast cancer and of failed early diagnosis by screening mammography.
To compare the screening performance of abbreviated breast MRI and digital breast tomosynthesis in women with dense breasts, the cross-sectional study with longitudinal follow-up was conducted at 48 academic, community hospitals, and private practice sites in the United States (US) and Germany between December 2016 and November 2017 among average-risk women aged 40 to 75 years with heterogeneously dense or extremely dense breasts undergoing routine screening. Follow-up ascertainment of cancer diagnoses was complete through 12 September 2019.
All women underwent screening by both abbreviated breast MRI and digital breast tomosynthesis, performed in randomised order and read independently to avoid interpretation bias. The primary endpoint was the invasive cancer detection rate. Secondary outcomes included sensitivity, specificity, additional imaging recommendation rate, and positive predictive value (PPV) of biopsy, using invasive cancer and ductal carcinoma in situ (DCIS) to define a positive reference standard. All outcomes are reported at the participant level. Pathology of core or surgical biopsy was the reference standard for cancer detection rate and PPV; interval cancers reported until the next annual screen were included in the reference standard for sensitivity and specificity.
Among 1516 enrolled women, 1444 completed both examinations and were included in the analysis. Median age was 54 years (range, 40-75).
The reference standard was positive for invasive cancer with or without DCIS in 17 women and for DCIS alone in another 6. No interval cancers were observed during follow-up. Abbreviated breast MRI detected all 17 women with invasive cancer and 5 of 6 women with DCIS. Digital breast tomosynthesis detected 7 of 17 women with invasive cancer and 2 of 6 women with DCIS.
The invasive cancer detection rate was 11.8 (95% confidence interval [CI], 7.4-18.8) per 1000 women for abbreviated breast MRI vs 4.8 (95% CI, 2.4-10.0) per 1000 women for digital breast tomosynthesis, a difference of 7 (95% CI, 2.2-11.6) per 1000 women (exact McNemar p = 0.002).
For detection of invasive cancer and DCIS, sensitivity was 95.7% (95% CI, 79.0%-99.2%) with abbreviated breast MRI vs 39.1% (95% CI, 22.2%-59.2%) with digital breast tomosynthesis (p = 0.001) and specificity was 86.7% (95% CI, 84.8%-88.4%) vs 97.4% (95% CI, 96.5%-98.1%), respectively (p < 0.001).
The additional imaging recommendation rate was 7.5% (95% CI, 6.2%-9.0%) with abbreviated breast MRI vs 10.1% (95% CI, 8.7%-11.8%) with digital breast tomosynthesis (p = 0.02) and the PPV was 19.6% (95% CI, 13.2%-28.2%) vs 31.0% (95% CI, 17.0%-49.7%), respectively (p = 0.15).
The authors wrote that further research is needed to better understand the relationship between screening methods and clinical outcome.
An accompanied editorial underlines that in February 2019, federal law directed the US Food and Drug Administration to oversee a mammographic density–reporting process for the entire country. Currently, legislation addressing communication regarding breast density is in place for a majority of US states.
The authors of the current study should be congratulated for their successful effort in generating high-level evidence regarding improved breast cancer screening and early detection in women with increased risk associated with mammographic density through the conduct of a large prospective clinical trial. The editorialists emphasized that discussion of the challenges associated with broadened applications of breast MRI technology does not represent a reason to abandon exciting advances in breast imaging. However, it does underscore the obligation to strive for equitable access to such advances. Another editorial article describes the study results as promising, but that further evaluation is required prior to widespread implementation.
- Comstock CE, Gatsonis C, Newstead GM, et al. Comparison of Abbreviated Breast MRI vs Digital Breast Tomosynthesis for Breast Cancer Detection Among Women With Dense Breasts Undergoing Screening. JAMA 2020;323(8):746-756. doi:10.1001/jama.2020.0572.
- Newman LA, Yip C-H. Options for Addressing the Dilemma of Managing Dense Breasts. JAMA Surg. Published online 25 February 2020. doi:10.1001/jamasurg.2020.0280
- Tosteson ANA. An Abbreviated MRI Protocol for Breast Cancer Screening in Women With Dense Breasts. Promising Results, but Further Evaluation Required Prior to Widespread Implementation. JAMA. 2020;323(8):719-721. doi:10.1001/jama.2020.0357