MRI Background Parenchymal Enhancement and Risk of Breast Cancer


Key Points

  • Increasing BPE was associated with a significantly increased risk of breast cancer.
  • Risk was increased across categories of breast density.

In a population-based study reported in the Journal of Clinical Oncology, Arasu and colleagues found that increased breast magnetic resonance imaging (MRI) background parenchymal enhancement was associated with an increased risk of breast cancer, with risk being independent of breast density.

The study involved data from women undergoing breast MRI in the Breast Cancer Surveillance Consortium from 2005 to 2015 using qualitative background parenchymal enhancement assessments of minimal, mild, moderate, or marked. Breast density was evaluated with mammography performed within 5 years of MRI. Among women diagnosed with breast cancer, the first background parenchymal enhancement assessment was included if it occurred more than 3 months before diagnosis.

Association With Breast Cancer Risk

The median follow-up was 2.8 years. Among 4,247 women included in the analysis, 176 developed breast cancer, including invasive disease in 129 and ductal carcinoma in situ in 47. More women with cancer had mild, moderate, or marked background parenchymal enhancement vs women without cancer (80% vs 66%).  

Compared with minimal background parenchymal enhancement, increasing enhancement was associated with significantly increased risk, with hazard ratios (HRs) of 1.80 (95% confidence interval [CI] = 1.12–2.87) for mild, 2.42 (95% CI = 1.51–3.86) for moderate, and 3.41 (95% CI = 2.05–5.66) for marked enhancement.

Compared with women with minimal enhancement and almost entirely fatty or scattered fibroglandular breast density, breast cancer risk was significantly increased among those with mild, moderate, or marked enhancement and almost entirely fatty or scattered fibroglandular breast density (HR = 2.30, 95% CI = 1.19–4.46) or heterogeneous or extremely dense breasts (HR = 2.61, 95% CI = 1.44–4.72; P = .82 for interaction). The combined categories of mild, moderate, and marked background parenchymal enhancement were associated with increased risk of 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).

The investigators concluded, “[Background parenchymal enhancement] is associated with future invasive breast cancer risk independent of breast density. [Background parenchymal enhancement] should be considered for risk prediction models for women undergoing breast MRI.”

Vignesh A. Arasu, MD, of Kaiser Permanente Medical Center and the University of California, San Francisco, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by a National Cancer Institute–funded Breast Cancer Surveillance Consortium program project and grants from the National Cancer Institute, Patient-Centered Outcomes Research Institute, and Agency for Healthcare Research and Quality. The study authors’ full disclosures can be found at

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.