Magnetic resonance imaging features of breast cancer according to intrinsic subtypes: correlations with neoadjuvant chemotherapy effects
Hiroko Kawashima
0
1
2
Masafumi Inokuchi
0
2
Hiroyuki Furukawa
0
2
Hiroko Ikeda
2
Seiko Kitamura
2
0
Section of Breast Oncology, Kanazawa University Hospital
, 13-1 Takara-machi, Kanazawa 920-8641,
Japan
1
Department of Quantum Medical Technology, Graduate School of Medical Science, Kanazawa University
, 5-11-80 Kodatsuno, Kanazawa 920-0942,
Japan
2
LA luminal A, LB luminal B, LH2 luminal-HER2, H2 HER2, TN triple-negative
Purpose: The purpose of this study was to evaluate the magnetic resonance imaging (MRI) features of breast cancer according to intrinsic subtypes and to investigate whether the MRI and immunohistochemical findings were related to neoadjuvant chemotherapy (NAC) effects. Materials and methods: The MRI in 116 women with breast cancers who underwent NAC was reviewed. The mass margin, presence of intratumoral necrosis, tumor extension around the mass, relative signal enhancement (RSE), and kinetic curve pattern were analyzed. We investigated the possible correlations between MRI findings and the effects of NAC. Results: An irregular mass margin was significantly associated with luminal-A cancers, while a smooth mass margin was associated with human epidermal growth factor receptor2 (HER2) cancers. Intratumoral necrosis was significantly associated with triple-negative cancers. Tumor extension around the mass was significantly infrequent in luminal-B cancers and frequent in HER2 cancers. Luminal-B and HER2 cancers showed a significantly higher RSE at 2 min than Luminal-A cancers. Estrogen receptor (ER)-positive cancers, HER2-negative cancers, and presence of intratumoral necrosis were significantly associated with the NAC non-response. Conclusions: Several MR features can be used to predict the intrinsic subtype of breast cancers. ER-positivity, HER2-negativity, and presence of intratumoral necrosis were significantly associated with NAC non-response.
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Introduction
It has become clear that breast cancers can be divided
into biologically different intrinsic subtypes by gene
expression analysis (Perou et al. 2000; Sorlie et al. 2001;
Perou & Borresen-Dale 2011; Brenton et al. 2005). In
clinical practice, it is common to determine the patients
intrinsic subtype using an immunohistochemical technique
(Tamimi et al. 2008), and a therapeutic plan is formed based
on each intrinsic subtype. From this trend, diagnosing
breast cancer imaging while keeping the intrinsic subtype
in mind is becoming a more widespread practice.
Neoadjuvant chemotherapy (NAC) has been the
standard treatment for locally-advanced breast cancer (Makhoul
& Kiwan 2011). NAC is mainly designed to reduce the
tumor size, thereby permitting breast-conserving surgery
(Liu et al. 2010). Other advantages of NAC are that
systemic therapy may be initiated earlier, and it enables
evaluation of a patients response to chemotherapy (Kaufmann
et al. 2007; Kaufmann et al. 2006). Conversely, a
NACrelated disadvantage is the delay of surgical treatment in
patients who do not respond to chemotherapy. If we can
predict the final chemotherapeutic response during earlier
NAC courses, an earlier and optimized treatment regimen
is possible, thereby improving patient prognosis (Chollet
et al. 2002; Montagna et al. 2010).
The purpose of this study was to evaluate the magnetic
resonance imaging (MRI) features of breast cancer
according to the intrinsic subtypes, and to investigate whether the
MRI and immunohistochemical findings were related to
NAC effects.
Materials and methods
Patients and treatment
Kanazawa University Medical Ethical Review Board
approved this retrospective study, and the requirement for
informed consent was waived. We enrolled patients with
breast cancer who underwent NAC at our hospital
between March 2008 and January 2013. A core biopsy of
the tumor was performed prior to NAC to determine the
histological diagnosis, hormone receptor status, human
epidermal growth factor receptor 2 (HER2) overexpression
status, and Ki-67 labeling index. We divided patients into
five intrinsic subtypes. The subjects included 116 women
(24 luminal A, 15 luminal B, 14 luminal-HER2, 23 HER2,
and 40 triple-negative cancers) (Table 1). All cases showed
mass formation and the mean maximal tumor size was 28
mm (range, 13-69 mm). The Ki-67 labeling index has not
measured for the initial 42 cases; therefore, we judged
luminal A or B status according to proliferative parameters
such as the nuclear grade.
The therapeutic schedule and treatment plan were
explained to the patient, and informed consent was obtained
from all patients. The standard protocol is four cycles of a
combination of 100 mg/m2 epirubicin, 500 mg/m2
cyclophosphamide, and 500 mg/m2 fluorouracil every 3 weeks
(FEC4), followed by four cycles of 75 mg/m2 doxetaxel
every 3 weeks (DOC4).
Magnetic resonance imaging
MRI was performed on a 3.0 T magnet (Signa HDxt 3.0 T,
GE Healthcare, Tokyo, Japan) using an eight-channel breast
phased array coil. The patients underwent imaging while
in the pron (...truncated)