© 2007 European Society for Medical Oncology
letters to the editor |
MRI features of breast cancer: a correlation study with HER-2 receptor
Limited literature is available correlating magnetic resonance imaging (MRI) features with molecular biomarkers expressed in invasive breast cancer. It is our opinion that this area needs to be explored. We hypothesize that the association of HER-2 overexpression in invasive ductal carcinoma (IDC) of breast might show a difference in MRI phenotype. Our study attempts to make comparative analysis of morphological MRI features based on American College of Radiology, Breast Imaging Reporting and Data System Atlas (BI-RADS atlas or ACR BI-RADS lexicon) [1] between HER-2-positive and -negative IDC.Retrospective blind review of breast MRI was carried out for 78 histologically proven IDC patients (30 HER-2 positive and 48 HER-2 negative), presenting from January 2003 to December 2005. Breast MRI was carried out after the institutional review board approval and informed consent was obtained for this Health Insurance Portability and Accountability Act (HIPPA, enacted by the US Congress in 1996)-compliant study.
The MRI study was carried out using a 1.5 T magnetic resonance scanner with a standard bilateral breast coil (Philips Medical Systems, Cleveland, OH). Pre-enhanced T1W axial and sagittal images and dynamic axial imaging were acquired. Images were interpreted by two breast radiologists who were experienced in breast MRI. The diagnosis of breast lesion was based on the morphologic and enhancement kinetic features of ACR BI-RADS-MRI lexicon. For patients undergoing MR spectroscopy, single-voxel method was carried out using a point-resolved spectroscopic sequence after the completion of MRI. The absolute Cho concentration was calculated using the method introduced by Bolan et al. [2], and was expressed in units of mmol/kg.
Table 1 summarizes the comparative analysis of MRI features associated with HER-2-positive and -negative IDC. Significantly, more number of IDC in the HER-2-positive category showed multifocal lesions (Figure 1) as compared with the HER-2-negative category (16/28, 57.1% versus 7/45, 15.5%; P < 0.001). On MRI, 11 of 30 (36.7%) HER-2-positive IDC and 8 of 50 (16%) HER-2-negative IDC showed positive for axillary lymph nodes metastases (P = 0.035). Seven of eight HER-2-positive patients and eight of nine HER-2-negative patients underwent magnetic resonance spectroscopic examination for choline measurement and showed a lesion 
1 cm. A significant difference was seen in the number of patients showing positive choline peak (4/7 in HER-2-positive group versus 0/8 in HER-2-negative group; P = 0.013). Table 2 compares tumor morphology and enhancement kinetic pattern for mass type lesions between HER-2-positive and HER-2-negative breast cancer. No significant difference was found regarding lesion shape, lesion margin, internal enhancement pattern, and enhancement kinetics patterns between HER-2-positive and HER-2-negative breast cancer.
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The significantly larger number of multifocal lesions and metastatic lymph nodes on breast MRI in patients with HER-2/neu overexpression found in our study indicated a more invasive behavior and greater metastatic potential. This may be explained by the study of Dragowska et al. [3] who suggested that HER-2/neu overexpression may be linked with overall increased tumor viability and a significant increase in the population of viable hypoxic cells. Giatromanolaki et al. [4] further showed that hypoxia-inducible factors-2 alpha overexpression is related to high metastatic potential. Thus, increased tumor viability with HER-2/neu overexpression may be the reason for more number of multifocal lesion and metastatic lymph nodes on MRI in our study. Our study also demonstrated significantly more number of tumors for similar tumor size with detectable Cho in the HER-2-positive group compared with the HER-2-negative group (4/7 versus 0/8). It was found that forced overexpression of HER-2/neu in a human mammary epithelial tumor cell line resulted in a dramatic increase in levels of Cho-containing compounds [5].
funding
National Institutes of Health/National Cancer Institute (R01 CA90437); California Breast Cancer Research Program (BCRP) (9WB-0020).
1 Tu and Yuen Center for Functional Onco-Imaging
2 Department of Surgery
3 Department of Medicine, University of California, Irvine, CA, USA
4 Department of Radiology, China Medical University Hospital, Taichung, Taiwan
* E-mail: jeonhc{at}uci.edu
References
1. American College of Radiology. Breast Imaging Reporting and Data System Atlas (BI-RADS Atlas) (2003) Reston, VA: American College of Radiology.
2. Bolan PJ, Meisamy S, Baker EH, et al. In vivo quantification of choline compounds in the breast with 1H MR spectroscopy. Magn Reson Med (2003) 50:1134–1143.[CrossRef][Web of Science][Medline]
3. Dragowska WH, Warburton C, Yapp DT, et al. HER-2/neu overexpression increases the viable hypoxic cell population within solid tumors without causing changes in tumor vascularization. Mol Cancer Res (2004) 2:606–619.
4. Giatromanolaki A, Sivridis E, Fiska A, Koukourakis MI. Hypoxia-inducible factor-2 alpha (HIF-2 alpha) induces angiogenesis in breast carcinomas. Appl Immunohistochem Mol Morphol (2006) 14:78–82.[CrossRef][Web of Science][Medline]
5. Aboagye EO, Bhujwalla ZM. Malignant transformation alters membrane choline phospholipid metabolism of human mammary epithelial cells. Cancer Res (1999) 59:80–84.
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