Annals of Oncology Advance Access originally published online on November 20, 2007
Annals of Oncology 2007 18(12):2042-2043; doi:10.1093/annonc/mdm504
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© 2007 European Society for Medical Oncology
letters to the editor |
Triple-negative breast cancer: MRI features in 29 patients
Triple-negative (TN) breast cancers were defined as those which tested negative for estrogen receptor (ER), progesterone receptor (PR), and HER2. TN breast cancers account for 12%–26% of all types of breast cancers [1–5]. TN tumors were aggressive and were usually diagnosed at a later stage [5]. About 85% of TN phenotypic breast cancers are deemed to be basal like and have a clinical behavior similar to basal-like tumors [2]. The most common histological types for TN breast cancer were invasive ductal carcinomas and metaplastic carcinomas [2]. Histologically, TN cancers are poorly differentiated, mainly of high histologic grade and with high mitotic index [1, 6]. Imaging features of this clinically important subtype of breast cancer are not well known. This study aimed to analyze its magnetic resonance imaging (MRI) features.In a full review of our breast MRI database from 2002 to 2006, 29 pathologically proven TN breast cancer patients (25–82 years old, mean 50, median 46) were analyzed. Twenty-five patients (25/29, 86%) were diagnosed with pure invasive ductal carcinoma and four patients (14%) with metaplastic breast cancer, including three with ductal and squamous components and one with ductal and chondroid components. The MRI study was carried out on a 1.5-T Phillips Eclipse magnetic resonance (MR) scanner with a standard bilateral breast coil (Philips Medical Systems, Cleveland, OH). After mid-2005, nine patients also received single-voxel proton MR spectroscopy, using point-resolved spectroscopic (PRESS) sequence for the correct localization of the volume of the centered lesion of interest, for detection and quantification of choline. The imaging protocol consisted of precontrast sagittal spin echo T1-weighted imaging and dynamic contrast-enhanced axial 3D SPGR (RF-FAST) T1-weighted imaging. The sequence was repeated 16 times, four pre-contrast, and 12 post-contrast sets after injection of Omniscan® (1 cc/10 lbs body weight). After the dynamic scan was completed, subtraction images and the maximum intensity projections (MIPs) were generated for tumor size measurements. The enhancement kinetics curves were analyzed from areas showing the brightest enhancement in the lesion. The lesion morphology and enhancement kinetic features were defined according to the Breast imaging reporting and data system atlas published by the American College of Radiology (BI-RADS atlas or ACR BI-RADS lexicon) [7]. The morphologic criteria included mass-type lesion [focus/foci (<5 mm), mass (>5 mm)] and non-mass type of enhancement (focal area, linear, ductal, segmental, regional, multiple regions, and diffuse enhancement). The evaluation of enhancement kinetic curve was on the basis of initial (within the first 2 min or when the curve starts to change), and late phases (after 2 min or after the change). The presence of abnormal skin enhancement of the breast and associated axillary lymph nodes were also recorded.
A radiologist with 2 years' experience interpreting breast MR analyzed the MR imaging features. Table 1 shows the demonstrated MRI features in these 29 patients. One patient had bilateral breast cancer and six patients (21%) had multiple cancer foci in the same breast. Tumor size ranged from 4 mm to 10 cm (4.1 ± 2.7 cm). The average tumor size was much bigger than the non-TN-type breast cancer. Twenty-seven patients (27 of 29 patients, 93%) had tumor >1.5 cm, and 10 patients had tumor <5 cm with prominent skin enhancement (34%), which raised the suspicion of T4 stage with dermal lymphatic invasion (Figure 1). Overall, six patients (21%) were T1 stage, 12 (41%) were T2, and 11 (38%) were T3 or above. This is consistent with the findings of Haffty et al. [1] and Rakha et al. [2] reporting that TN tumors were larger (>1.5 cm) or had a higher T staging than non-TN tumors (79% versus 62%, 42% versus 21%, respectively). Except for one patient presenting with a non-mass type of regional enhancement, the other 28 patients (97%) had mass-type lesions. Twenty-six of the 28 mass-type lesions (93%) were >1.5 cm and showed strong and/or heterogeneous enhancements. Rim enhancement, a specific sign of malignancy on breast MRI, was identified in 12 patients (41%). Twenty-two lesions had documented enhancement kinetic curves, and all showed the typical malignant kinetic feature with rapid up-slope followed by washout (100%). The morphological and kinetics features are in accordance with MRI features of invasive ductal carcinoma. Fourteen patients (14 of 29 patients, 48%) showed identifiable lymph nodes in the axillary region. It was reported that in the TN and non-TN tumors with the same positive nodal status, the 5-year nodal relapse-free rate was significantly different between the two groups and the TN subtype was more frequently associated with a higher pathologic stage of the nodal status than the non-TN subtype [1]. Seven of the nine patients (78%) undergoing MR spectroscopy showed quantifiable choline level ranging from 0.4 to 4.9 mmol/kg (mean 2.6). To our best knowledge, this was the first reported data on MR spectroscopy of TN tumors.
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In conclusion, our preliminary observation showed that most of TN breast cancers were mass-type lesions, which was dominated by their ductal phenotype with typical malignant enhancement kinetics on MRI. A large proportion of TN breast cancers were characterized with axillary lymph node metastases and late stage of diagnosis with large tumor size and advanced tumor growth. All these features may contribute to its aggressive malignant behavior and worse outcome.
funding
NIH/NCI (R01 CA90437) and California BCRP (# 9WB-0020).
1 Center for Functional Onco-Imaging, University of California, Irvine, CA, USA
2 Department of Radiology, China Medical University Hospital, Taichung, Taiwan
3 Department of Pathology and Laboratory Medicine
4 Department of Medicine, University of California, Irvine, CA, USA
* (E-mail: jeonhc{at}uci.edu)
References
1. Haffty BG, Yang Q, Reiss M, et al. Locoregional relapse and distant metastasis in conservatively managed triple negative early-stage breast cancer. J Clin Oncol (2006) 24(36):5652–5657.
2. Rakha EA, El-Sayed ME, Green AR, et al. Prognostic markers in triple-negative breast cancer. Cancer (2007) 109(1):25–32.[CrossRef][Medline]
3. Cleator S, Heller W, Coombes RC. Triple-negative breast cancer: therapeutic options. Lancet Oncol (2007) 8(3):235–244.[CrossRef][Web of Science][Medline]
4. Carey LA, Perou CM, Livasy CA, et al. Race, breast cancer subtypes, and survival in the Carolina Breast Cancer Study. JAMA (2006) 295:2492–2502.
5. Bauer KR, Brown M, Cress RD, et al. Descriptive analysis of estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, and HER2-negative invasive breast cancer, the so-called triple-negative phenotype: a population-based study from the California Cancer Registry. Cancer (2007) 109(9):1721–1728.[Medline]
6. Siziopikou KP, Cobleigh M. The basal subtype of breast carcinomas may represent the group of breast tumors that could benefit from EGFR-targeted therapies. Breast. (2007) 16(1):104–107.[CrossRef][Medline]
7. American College of Radiology. Breast Imaging Reporting and Data System Atlas (BI-RADS atlas). (2003) Reston, VA: American College of Radiology.
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