Background parenchymal enhancement observed on breast MRI appeared to be strongly predictive of risk for breast cancer, regardless of breast density, according to a study published in Journal of Clinical Oncology.
“The incorporation of breast density in breast cancer risk models, as well as state-mandated reporting of mammographic breast density to women, underscores the central role of imaging biomarkers in risk assessment,” Vignesh Arasu, MD, a radiologist affiliated with Kaiser Permanente Medical Center and University of California, San Francisco, and colleagues wrote. “Recent studies have explored the predictive value of other breast imaging biomarkers, and accumulating evidence suggests elevated background parenchymal enhancement (BPE) assessed on breast MRI may predict primary breast cancer risk.”
BPE — a phenomenon on breast MRI in which normal breast tissue demonstrates signal enhancement related to uptake of gadolinium-based IV contrast — may depict greater
tissue microvascularity or permeability regulated by estrogen, and it also may represent tissue at risk for neoplasia.
Arasu and colleagues investigated associations between BPE and breast cancer risk among 4,247 women (82% aged younger than age 60 years; 81% white or non-Hispanic) who underwent breast MRI between 2000 and 2015. The researchers used qualitative evaluations of BPE as minimal, mild, moderate or marked, and they assessed breast density on mammography, which was performed within 5 years of MRI.
For women diagnosed with breast cancer, researchers included the first BPE evaluation if it took place more than 3 months prior to diagnosis.
A total of 176 of the women examined developed breast cancer (invasive, n = 129; ductal carcinoma in situ, n = 47) during median follow-up of 2.8 years.
Results showed a higher rate of mild, moderate or marked BPE in women with cancer vs. among controls (80% vs. 66%).
Compared with minimal BPE, increasing BPE levels appeared associated with significantly elevated breast cancer risk (mild, HR = 1.8; 95% CI, 1.12- 2.87; moderate, HR = 2.42; 95% CI, 1.51-3.86; marked, HR = 3.41; 95% CI, 2.05-5.66).
A higher proportion of women who developed cancer had dense breasts (72% vs. 65%). Women with dense breasts had a higher risk for breast cancer than women with almost entirely fatty or scattered fibroglandular breast density (HR = 1.54; 95% CI, 0.97-2.44).
Also, those with cancer were more likely to have mild, moderate or marked BPE and high breast density (57% vs. 38%).
Women with high breast density and minimal BPE did not have a statistically significant increased risk for breast cancer (HR =1.25; 95% CI, 0.61-2.54) compared with women with low breast density and minimal BPE. Conversely, women with low breast density and mild, moderate or marked BPE had significantly higher risk for developing breast cancer (HR = 2.3; 95% CI, 1.19-4.46).
Analyses showed associations between combined mild, moderate or marked BPE and significantly elevated risk for invasive cancer (HR = 2.73; 95% CI, 1.66-4.49) but not ductal carcinoma in situ (HR = 1.48; 95% CI, 0.72-3.05).
“We found BPE to be a strong predictor of future breast cancer risk, which was independent of breast density and other established risk factors,” the researchers wrote. “BPE should be considered for incorporation into risk prediction models for women undergoing MRI.” – by Jennifer Byrne
Disclosures: Arasu reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.