Background Parenchymal Enhancement and Fibroglandular Tissue Proportion on Breast MRI: Correlation with Hormone Receptor Expression and Molecular Subtypes of Breast Cancer

Abstract

IntroductionBreast cancer is the most common malignancy of women with a life-time risk up to 12% in USA (1). It is the second most common cause of death from cancer in women (2). In recent years, advancement in the knowledge of the biology of breast cancer has contributed to better understanding the nature of the disease. For therapeutic reasons, breast cancer is divided into four different molecular subtypes using molecular biomarkers: estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor 2 (HER2). Four molecular subtypes are identified: Luminal A, Luminal B, HER2 positive, and Triple Negative (3). Different subtypes present with distinct epidemiological risk factors, distinct disease prognoses, and different responses to systemic and local therapy (4)(5)(6)(7)(8). This knowledge has opened a new door in disease management toward personalized therapy. For example, luminal A cancers require hormonotherapy whereas triple negative tumors respond better to chemotherapy (3). Trastuzumab, which is directed against the HER2-neu receptor, is considered in the treatment of HER2 positive tumors (3). Luminal A and luminal B subtypes are more likely to develop bone metastases whereas triple negative subtypes are more likely to develop lung and brain metastases (9).Breast MRI is a common diagnostic tool in the management of breast diseases. It can be used for screening in a high-risk population, for determining the disease extent, or for problem solving to contribute in discordant results of mammography, ultrasonography or clinical findings. FGT proportion, which refers to the proportion of FGT to fat tissue of the breast, and BPE, which refers to the enhancement of normal breast parenchyma after contrast agent administration, are two imaging features of breast MRI. Breast density which reflects FGT composition is a well-known risk factor for breast malignancy. Women having a high amount of FGT content are also more likely to develop breast cancer (10). Similarly, a recent study reported that moderate or marked BPE is associated with a greater risk of developing breast cancer than minimal or mild BPE (11). Considering those known risk factors and the spectrum of breast cancers, one may suspect that FGT proportion and BPE of the same molecular subtypes may have some common properties. Breast Health 2017; 13: 27-33 DOI: 10.5152/tjbh.2016.3247 27 ABSTRACT Objective: To assess the relationship between background parenchymal enhancement (BPE) and fibroglandular tissue (FGT) proportion on breast magnetic resonance imaging (MRI) and hormone receptor expression and molecular subtypes in invasive breast cancer. Materials and Methods:This retrospective study enrolled 75 breast cancer patients who underwent breast MRI before treatment. T1-weighted images were reviewed to determine the FGT proportion, and contrast-enhanced fat-suppressed T1-weighted images were reviewed to determine BPE. Estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2-neu (HER2) status, and mole...

Association between MRI background parenchymal enhancement and lymphovascular invasion and estrogen receptor status in invasive breast cancer

“… 44 Estrogen and progesterone levels are associated with BPE 38,39 ; therefore, it could be hypothesized that BPE is associated with ER and PR statuses in patients with breast cancer. The present study suggests that BPE was positively associated with ER, as supported by Dontchos et al, 30 Kim et al, 42 and Ozturk et al 45 Progesterone is an important intermediate for the biosynthesis of estrogen, androgen, and adrenocorticosteroids. The structure and action mechanism of PR are also complex.…”

Association of breast cancer with MRI background parenchymal enhancement: the IMAGINE case-control study

“…We also found that the hormone receptor status of tumors was independently associated with BPE in the unaffected breast among postmenopausal cases. Two small clinical studies previously identified univariable associations between hormone receptors and BPE [ 32 , 33 ] while others did not identify any associations [ 34 – 36 ]. This study is the first to report the association in a large population of women with breast cancer using a multivariable approach, but these results should be interpreted with caution and require confirmation in future studies.…”

Comparison of Segmentation Methods in Assessing Background Parenchymal Enhancement as a Biomarker for Response to Neoadjuvant Therapy

“…BPE observed in breast fibroglandular tissue (FGT) shows an association with breast cancer risk (16)(17)(18)(19) and has also been investigated for use as an imaging biomarker to predict NAC response (20)(21)(22). Studies have shown BPE to be subtype-dependent with positive association for hormone receptor status (23,24). Currently, 4 categories of BPE are qualitatively defined in the Breast Imaging Reporting and Data System (BI-RADS) atlas: minimal, mild, moderate, and marked (25).…”