A review and meta-analysis published in the journal Radiology found MRI to be the most effective supplemental breast cancer screening method for women with dense breasts and negative mammogram results.
Mammography is the standard imaging modality for breast cancer screening—and in fatty breasts, it detects up to 98% of cancers, the authors noted. However, the sensitivity of mammography in extremely dense breasts is only 30% to 48%. Considering an estimated 47% of individuals screened in the US have dense breasts, which are also a risk factor for breast cancer development, supplemental screening in this population is recommended to increase the likelihood of identifying breast cancer in early stages.
“Our study was designed to evaluate the role of different supplementary screening tests in women of average or intermediate risk of breast cancer with dense breast tissue who had a negative screening mammogram,” study coauthor Vivianne Freitas, MD, MSc, assistant professor at the University of Toronto in Canada and staff radiologist at the Joint Department of Medical Imaging in Toronto, said in a statement. On a mammogram, both breast cancer and breast tissue appear white, making the identification of cancer more difficult in these patients, she explained.
The systemic review assessed data from 22 randomized clinical trials and prospective observational studies encompassing 261,233 screened patients overall. A total of 132,166 patients had dense breast tissue, had a negative mammogram, were at an average or intermediate cancer risk, and met all inclusion criteria; 541 cancer cases were missed at mammography but detected with supplemental screening.
The authors reviewed the incremental cancer detection rate (CDR), positive predictive value of recall (PPV1), positive predictive value of biopsies performed (PPV3), and interval CDRs of various supplemental imaging methods. These included digital breast tomosynthesis, handheld ultrasound, automated whole breast ultrasound, and MRI.
MRI outperformed other modalities of supplemental screening in the study, with an incremental CDR of 1.54 per 1000 screenings (95% CI, 0.74-2.33; P < .001). The invasive disease CDR was 1.31 per 1000 screenings (95% CI, 0.57-2.06; P < .001), and the CDR for ductal carcinoma in situ was 1.91 per 1000 screenings (95% CI, 0.10-3.72; P < .04).
Handheld ultrasound had an incremental CDR of –0.35 (95% CI, –0.7 to 0.08; P = .11), automated whole breast ultrasound had an incremental CDR of –0.26 (95% CI, –1.07 to 0.56; P = .53), and digital breast tomosynthesis had an incremental CDR of –0.14 (95% CI, –0.58 to 0.29; P = .51).
The study did not find any differences in in PPV1 and PPV3, and the relatively small number of studies prevented the authors from assessing interval cancer metrics. Other than MRI, there were no statistically significant differences in any metrics among the rest of the imaging modalities.
“MRI is far superior in terms of cancer detection compared to hand-held ultrasound, automated ultrasound and digital breast tomosynthesis,” Freitas said. “Our results about the role of MRI in supplementary screening will allow stakeholders to guide healthcare policies in this setting and direct further research.”
MRI still has pros and cons to consider, the authors noted. A limiting factor in the use of MRI for secondary screening is its high cost relative to other modalities, although abbreviated MRI could potentially be more cost-effective in due to shorter image acquisition and interpretation times. Another limitation is its lower accessibility compared with other methods due to a lack of sufficient MRI scanners worldwide, they added. Another possible concern is the need for contrast agent injection and the resulting accumulation of gadolinium in the brain, but the clinical significance of this aspect is not certain, according to the authors.
“Before we can advocate for wider application of breast MRI in these women, further evaluation of cost-effectiveness of breast MRI compared to other techniques, effect on mortality reduction, etc., will need to be studied,” Freitas said. “At the current time, availability and cost of the breast MRI remain the biggest barrier for widespread implementation.”
Hussein H, Abbas E, Keshavarzi S, et al. Supplemental breast cancer screening in women with dense breasts and negative mammography: a systematic review and meta-analysis. Radiology. Published online January 31, 2023. doi:10.1148/radiol.221785