Breast MRI superior to other supplemental methods for detecting cancer in dense breasts

Breast MRI was the most statistically effective supplemental screening tool for detecting cancer in dense breasts compared with other screening modalities, a study published in Radiology found.

Heba Hussein, MD, PhD, from the joint department of medical imaging-breast division at the University of Toronto, and colleagues pointed out that mammography detects “up to 98% of carcinomas in fatty breasts,” but its sensitivity declines to 30% to 48% in dense breasts.

Previous research has established that breast density is a risk factor for breast cancer. A 2007 New England Journal of Medicine study found that women with density in 75% or more of the mammogram had a greater risk for cancer compared with women with less than 10% density.

“Therefore, to overcome the limitation of mammography in this subgroup of patients, supplemental imaging tests have been suggested to increase the chance of detecting a tumor before it becomes symptomatic because delayed detection is associated with lower survival,” Hussein and colleagues wrote.

The most common supplemental screening methods include handheld breast ultrasound (HHBUS), automated whole-breast ultrasound (ABUS), digital breast tomosynthesis (DBT) and breast MRI. Although each possesses benefits and limitations, the researchers said there is a lack of clinical guidance on which method should be used for women with dense breasts and negative mammography for cancer.

To see which modality offers the greatest level of detection in this population, Hussein and colleagues performed a meta-analysis of 22 studies consisting of 261,233 screenings.

Of those patients, 132,166 had dense breasts and a negative mammogram. Overall, 541 cancers were missed during the mammography but were detected by supplemental screenings.

In a meta-regression analysis, the researchers reported that breast MRI was more effective in incremental cancer detection rate (CDR) per 1,000 screenings (CDR = 1.54; 95% CI, 0.74-2.33) compared with:

• HHBUS (CDR = -0.35; 95% CI, -0.77-0.08);
• ABUS (CDR = -0.26; 95% CI, -1.07-0.56); and
• DBT (CDR = -0.14; 95% CI, -0.58-0.29).

There was no difference in metrics among the remaining modalities when breast MRI was excluded, according to the researchers.

Additionally, the researchers found that breast MRI was superior in detecting even the smallest of invasive cancers (CDR = 1.31; 95% CI, 0.57-2.06) and ductal carcinoma in situ (CDR = 1.91; 95% CI, 0.1-3.72), which “according to previous studies may impact long-term survival.”

Although there were no statistically significant differences in the positive predictive values of the modalities, defined by Hussein and colleagues as “the total number of cases of cancer detected divided by the total number of recalled screening examinations based on abnormal findings at screening examination and based on biopsy results,” breast MRI did have higher values for both outcomes compared with HHBUS and ABUS.

“This may represent another important benefit of MRI in this setting because higher false-positive rates increase patient anxiety and the cost burden on the health care system from additional imaging workup, short-interval follow-up, or biopsy,” they wrote.

While the researchers acknowledged the superiority of breast MRI compared with its screening counterparts, they also underlined the existing barriers to increased MRI usage, which includes limited worldwide availability due to insufficient scanners and high costs.

“It is too early to advocate worldwide for the implementation of supplemental MRI because more studies are needed to make conclusions about the relative effectiveness of the other modalities and because the effectiveness of MRI, in terms of mortality reduction and cost-effectiveness analysis, has not yet been examined; this is the next logical step to consolidate these preliminary findings,” they concluded.

References:

• Boyd N, et al. N Engl J Med. 2023;doi:10.1056/NEJMoa062790
• Breast MRI effective at detecting cancer in dense breasts. https://www.eurekalert.org/news-releases/978113. Published Jan. 31, 2023. Accessed Jan. 31, 2023.
• Hussein H. Radiology. 2023;doi:10.1148/radiol.221785