Compared to other common supplemental screening methods, breast magnetic resonance imaging (MRI) was superior at detecting breast cancer in patients with dense breasts, according to a new study published by Hussein et al in Radiology.
Background
Breast cancer is one of the leading causes of cancer mortality among female patients. Roughly 47% of U.S. individuals who identify as female have dense breasts—which has been identified as an independent risk factor for breast cancer. Individuals with dense breasts have a higher amount of glandular tissue and fibrous connective tissue and low amounts of fatty tissue in the breasts.
While screening mammograms may effectively detect up to 98% of tumors in fatty breasts, breast cancer is more difficult to detect in dense breasts. This can result in a negative mammogram, giving patients false reassurance.
“Breast cancer masses appear white on a mammogram, and dense tissue also appears white—which makes finding breast cancers within dense breast tissue harder for radiologists,” stressed study coauthor Vivianne Freitas, MD, MSc, Assistant Professor of Radiology at the University of Toronto and staff radiologist at the Joint Department of Medical Imaging at the University Health Network. Supplemental screening—including the hand-held breast ultrasound, automated breast ultrasound, digital breast tomosynthesis, and breast MRI—may be required to assist with cancer detection in patients with dense breasts.
“Our study was designed to evaluate the role of different supplementary screening tests in [female patients] of average or intermediate risk of breast cancer with dense breast tissue who had a negative screening mammogram,” Dr. Freitas explained.
MRI is far superior in terms of cancer detection compared [with a] hand-held ultrasound, automated ultrasound, and digital breast tomosynthesis…. Our results about the role of MRI in supplementary screenings will allow stakeholders to guide health-care policies in this setting and direct further research.— Vivianne Freitas, MD, MSc
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Study Methods and Results
To measure which screening method was the most beneficial to patients with dense breasts, researchers conducted a meta-analysis of 22 studies that included 261,233 patients screened for breast cancer. Ten of the studies covered hand-held breast ultrasound, four studies covered automated breast ultrasound, three studies covered breast MRI, and eight studies reported on digital breast tomosynthesis. Among the patients involved in the study, 132,166 patients had dense breasts and negative mammograms.
Risk assessment models have been used to identify patients with an average or intermediate risk of developing breast cancer. In the United States, individuals who identify as female with an estimated lifetime risk of 12% to 13% of developing breast cancer are considered average risk. Factors that elevate the risk to intermediate include being previously treated for breast cancer or having previous breast biopsies with high-risk lesions. High-risk patients—with a lifetime risk of 20% or higher—were excluded from the study since the benefits of breast MRI were already established in high-risk populations.
The meta-analysis showed that among the 132,166 patients with dense breasts, a total of 541 breast cancers that were initially missed on mammograms were detected with supplemental screening methods. Breast MRI was the most effective screening method and was capable of detecting the smallest tumors. Excluding breast MRIs, there were no significant differences between the other supplemental screening methods.
Conclusions
“MRI is far superior in terms of cancer detection compared [with a] hand-held ultrasound, automated ultrasound, and digital breast tomosynthesis,” Dr. Freitas highlighted. “Our results about the role of MRI in supplementary screenings will allow stakeholders to guide health-care policies in this setting and direct further research.” While the results demonstrated the effectiveness of breast MRI in cancer detection, more research may be needed to fully evaluate its benefits compared to other breast cancer screening methods.
“Before we can advocate for wider application of breast MRI in these [patients], further evaluation of [the screening’s] cost-effectiveness compared to other techniques, effect on mortality reduction, etc, will need to be studied,” Dr. Freitas noted, concluding, “At the current time, availability and cost of the breast MRI remain the biggest barriers for widespread implementation.”
Disclosure: For full disclosures of the study authors, visit pubs.rsna.org.
