DOI:10.2214/AJR.04.1520
AJR 2006; 186:431-439
© American Roentgen Ray Society
Breast-Conserving Surgery After Chemotherapy: Value of MDCT for Determining Tumor Distribution and Shrinkage Pattern
Mitsuhiro Tozaki1,
Tadashi Kobayashi2,
Shinji Uno2,
Keisuke Aiba2,
Hiroshi Takeyama3,
Hisashi Shioya3,
Isao Tabei3,
Yasuo Toriumi3,
Masafumi Suzuki4 and
Kunihiko Fukuda1
1 Department of Radiology, The Jikei University School of Medicine, 3-25-8
Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan.
2 Department of Clinical Oncology, The Jikei University School of Medicine,
Tokyo 105-8461, Japan.
3 Department of Surgery, The Jikei University School of Medicine, Tokyo
105-8461, Japan.
4 Department of Pathology, The Jikei University School of Medicine, Tokyo
105-8461, Japan.
Received September 26, 2004;
accepted after revision January 31, 2005.
Address correspondence to M. Tozaki
(tozaki{at}mtf.biglobe.ne.jp).
Abstract
OBJECTIVE. For this study, we investigated the usefulness of MDCT in
assessing the extent of residual breast cancer after neoadjuvant chemotherapy.
To ensure the success of breast-conserving surgery, we evaluated the
usefulness of determining the tumor distribution before neoadjuvant
chemotherapy and the shrinkage pattern after neoadjuvant chemotherapy.
SUBJECTS AND METHODS. MDCT before and after neoadjuvant chemotherapy
was performed in 46 consecutive patients with 47 locally advanced breast
cancers. The distribution pattern of contrast enhancement on MDCT before
neoadjuvant chemotherapy was classified into five categories: solitary lesion,
grouped lesion (localized lesion with linear, spotty, or linear and spotty
enhancement), separated lesion (multiple foci of contrast enhancement), mixed
lesion (grouped lesion with multiple foci), and replaced lesion (diffuse
contrast enhancement in whole quadrants).
RESULTS. There was agreement between the MDCT assessment and
pathologic findings in 44 (94%) of the 47 tumors. In the partial response
group with nonreplaced lesions, MDCT revealed three shrinkage patterns:
pattern 1a, concentric shrinkage without surrounding lesions; pattern 1b,
concentric shrinkage with surrounding lesions; and pattern 2, shrinkage with
residual multinodular lesions. Breast-conserving surgery was performed
successfully in 14 patients including complete response cases that were
detected on the basis of MDCT findings and partial response cases that were
detected on the basis of observation of pattern 1 shrinkage. In all five
patients with pattern 2 shrinkage, CT underestimated the residual tumor extent
by more than 2 cm.
CONCLUSION. MDCT classification of tumor distribution before
neoadjuvant chemotherapy and of shrinkage patterns after neoadjuvant
chemotherapy is important in the preoperative evaluation of patients
undergoing breast-conserving surgery.
Keywords: breast cancer • breast-conserving surgery • chemotherapy • MDCT
Introduction
Recently, neoadjuvant chemotherapy has been used as standard therapy for
the management of locally advanced breast cancer
[1-4].
Several large randomized clinical trials have shown that neoadjuvant
chemotherapy is as effective as adjuvant chemotherapy and better permits
breast-conserving surgery [1,
2]. Thus, neoadjuvant
chemotherapy is the most appropriate treatment strategy for patients who wish
to conserve the breast but who have a tumor that is too large to permit
breast-conserving surgery [3].
The current purposes of neoadjuvant chemotherapy are to improve control of the
primary site and micrometastatic disease, observe chemosensitivity, and
increase the possibility that the patient may undergo breast-conserving
surgery. Also for breast-conserving surgery to be successful, it is important
to obtain precise information regarding the extent and distribution of the
breast cancer to avoid local recurrence.
Several studies have indicated that MRI is an accurate method for
preoperative assessment of breast cancer residua after neoadjuvant
chemotherapy
[5-12].
Helical CT has also been applied to accurately determine the extent of
residual breast cancer after neoadjuvant chemotherapy
[13,
14]. On the other hand, MDCT,
which first became clinically available in 1998, enables faster scanning, a
wider scan coverage area, and higher resolution of the volume data than
single-detector helical CT. The purpose of this study was to evaluate the
efficacy of MDCT in assessing the extent of residual cancer after neoadjuvant
chemotherapy. To ensure the success of breast-conserving surgery, we evaluated
the usefulness, in particular, of determining tumor distribution before
neoadjuvant chemotherapy and shrinkage pattern after neoadjuvant
chemotherapy.
Subjects and Methods
Patients and Neoadjuvant Chemotherapy Regimen
From October 1999 to May 2004, MDCT was performed before and after
neoadjuvant chemotherapy in 46 patients with 47 locally advanced breast
cancers (stage IIA-IIIB) that were diagnosed on the basis of clinical and
physical examination findings and the results of percutaneous core needle
biopsy. Patient characteristics and tumor classification are summarized in
Table 1. We informed all
patients of the potential benefits and risks of surgical planning based on
MDCT after neoadjuvant chemotherapy for locally advanced breast cancers, and
we obtained informed consent from all women.
All patients were treated with anthracycline and taxane-based chemotherapy,
usually for four to six cycles. Assessment of tumor response to neoadjuvant
chemotherapy was conducted by determining tumor volume, which was based on
orthogonal 2D measurements of the tumor, before and after chemotherapy.
Response to treatment was classified as follows: complete response (CR),
indicated by total disappearance of the breast mass; partial response (PR),
defined as a reduction of 50% or more of the product of the two largest
perpendicular dimensions; or no response (NR), including minor response, no
change, and progressive disease.
CT Protocol
An MDCT scanner (Somatom Volume Zoom, Siemens Medical Solutions) with four
detector bands was used. Patients were examined in the oblique supine
position, the same position as that for surgery. Dynamic CT, covering the
whole breast and axilla, was performed with 100 mL of nonionic contrast
material (iopamidol [Iopamiron 370, Nihon Schering]), which was injected at a
rate of 3 mL/sec. The first scan was started 60 sec after commencing contrast
injection (early phase). The second scan was started 4 min after the start of
injection (late phase). Early and late phase scanning were performed in 20-25
sec with four detector rows, 1-mm collimation, 500-msec rotation speed, 140
kV, 100 mAs, and pitch of 4-5. Multiplanar reformations (multiplanar
reconstructions) parallel to the thoracic wall were acquired to visualize the
extent of the breast cancer.
Distribution of Enhancement Before Chemotherapy
The distribution pattern of contrast enhancement was retrospectively
classified into five categories (Figs.
1A,
1B,
1C,
1D, and
1E): solitary lesion (localized
area of contrast enhancement), grouped lesion (localized lesion with linear,
spotty, or linear and spotty enhancement), separated lesion (multiple foci of
contrast enhancement), mixed lesion (grouped lesion with multiple foci), and
replaced lesion (diffuse contrast enhancement in whole quadrants).
Interpretation and Analysis
For the interpretations of MDCT images obtained before neoadjuvant
chemotherapy, detection of asymmetric focal enhancement on early phase
multiplanar reconstruction images of both breasts was regarded as positive
[15]. Symmetric enhancement
was defined as negative (normal or mastopathy). On MDCT performed after
neoadjuvant chemotherapy, residual enhancing lesions detected on late phase
multiplanar reconstruction images were regarded as positive
[16].
The shrinkage pattern after neoadjuvant chemotherapy was assessed. All the
MDCT images were retrospectively assessed by one experienced radiologist who
was blinded to the mammographic, sonographic, and histologic findings.
Surgical Approach and Histologic Evaluation
In our institution, breast-conserving surgery after neoadjuvant
chemotherapy was performed in women with a unifocal breast cancer with or
without surrounding intraductal extension of less than 3 cm in diameter and 2
cm or more from the nipple. Tumors were usually resected with a 2-cm surgical
margin. The resection line was determined with the clinical information and
late phase multiplanar reconstruction images obtained on MDCT after
neoadjuvant chemotherapy.
The mastectomy specimens were processed by serial gross sectioning at
approximately 1-cm intervals. Specimens obtained during breast-conserving
surgery were sliced into 5-mm contiguous sections. Cancer foci at the margin
were classified as positive. The histopathologic response to treatment was
classified as follows: pathologic CR, complete absence of residual breast
cancer; pathologic PR, reduction of 50% or more of the product of the two
largest perpendicular dimensions (it is necessary to approximate the size
parameters used in clinical response staging) or presence of predominant
hypocellular scar tissue surrounding the residual foci of invasive or in situ
carcinoma; or pathologic NR, which indicated minor response, no change, or
progressive disease.
Pathologic Correlation and Statistical Analysis
Histologic measurement of tumor size included not only the invasive foci
but also in situ ductal carcinoma and was used as the gold standard. The
largest dimension of cancer residua was taken as that perpendicular to the
plane of the section of the specimen. The size of the enhancing lesions as
determined by MDCT was also measured on the basis of the largest diameter.
Pearson's correlation coefficients were calculated to determine the
association between the MDCT and clinical examination measurements and
histologic size, and 95% confidence intervals (CIs) were calculated for each
correlation. The discrepancy of tumor extent between MDCT and histology was
calculated, and accuracy with a deviation of less than 2 cm in length was
evaluated. The relationship between tumor distribution on MDCT before
neoadjuvant chemotherapy and shrinkage pattern after neoadjuvant chemotherapy
and the histologic extent of the tumor was analyzed with Wilcoxon's rank sum
test.
Results
Mastectomy was performed in 32 patients and breast-conserving surgery in
13, and one patient underwent mastectomy and breast-conserving surgery. Based
on the gold standard histopathologic findings, one lesion (2%) showed
pathologic CR, 36 lesions (77%) showed pathologic PR, and 10 lesions (21%)
showed pathologic NR after neoadjuvant chemotherapy
(Table 2). The pathologic PR
group included six cases of ductal carcinoma in situ (DCIS).
Clinical Assessment and MDCT After Chemotherapy
The clinical assessment of tumor response was in agreement with the
pathologic findings in 42 (89%) of the 47 tumors
(Table 2). The clinical
assessment overestimated the degree of response in the remaining five cases,
including three cases of DCIS and a 23-mm DCIS with microinvasion; the
remaining case showed scattered invasive foci over a diameter of 30 mm without
mass formation (Table 2).
There was agreement between the MDCT assessment and pathologic findings in
44 (94%) of the 47 tumors (Table
2). The imaging findings overestimated the degree of response in
the three remaining cases, including two cases of DCIS; the remaining case
showed scattered invasive foci over a diameter of 30 mm, without mass
formation (Table 2).
In the analysis of all patients, clinical examination measurements showed a
moderate correlation with pathologic size (r = 0.57, p <
0.001), with a 95% CI of 0.34-0.74. The correlation between MDCT measurements
and histologic size was high (r = 0.84, p < 0.001), with
a 95% CI of 0.73-0.91 (Table
3). In the CR and PR groups, Pearson's correlation coefficient
between MDCT and histology was 0.84 (p < 0.001; 95% CI,
0.72-0.92), whereas it was 0.47 (p < 0.005; 95% CI, 0.18-0.69)
between clinical examination and histology.
View this table:
[in this window]
[in a new window]
|
TABLE 3: Mean Tumor Size Based on Clinical Examination and MDCT After Neoadjuvant
Chemotherapy and Correlation with Final Histologic Result
|
|
Distribution of Enhancement Before Neoadjuvant Chemotherapy
All the tumors were well visualized on the MDCT images obtained before
neoadjuvant chemotherapy. A solitary lesion was seen in 15 cases. Grouped
lesions were observed in 12 cases, including one with inflammatory cancer.
Separated lesions were seen in four cases, including three with inflammatory
cancers. Mixed lesions were seen in five cases, including one with
inflammatory cancer. Replaced lesions were seen in 11 cases, including six
with inflammatory cancers.
Shrinkage Pattern and Pathologic Correlation
In all the cases of replaced lesions, the shrinkage pattern was similar
(Figs. 2A,
2B, and
2C). Early phase CT images
acquired after neoadjuvant chemotherapy showed significantly decreased
enhancement effects. In contrast, late phase CT images showed gradual
enhancement in the original tumor bed (total field of tumor). Histologically,
numerous viable cells with fibrous tissue were found throughout the original
tumor bed.
View larger version (92K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A —48-year-old woman with inflammatory carcinoma of left breast
(replaced lesion: T4d N1). Early phase CT image of left breast acquired before
neoadjuvant chemotherapy shows diffuse enhancement in all quadrants.
Craniocaudal and transverse lines are drawn crossing over nipple.
|
|
View larger version (84K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B —48-year-old woman with inflammatory carcinoma of left breast
(replaced lesion: T4d N1). Early phase CT image acquired after neoadjuvant
chemotherapy reveals significantly decreased enhancement effect.
|
|
View larger version (97K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2C —48-year-old woman with inflammatory carcinoma of left breast
(replaced lesion: T4d N1). Late phase CT image acquired after neoadjuvant
chemotherapy shows diffuse enhancement in original tumor bed (total field of
tumor). Histologic evaluation of mastectomy specimen revealed 9.0-cm invasive
and in situ ductal carcinomas.
|
|
In the PR group with nonreplaced lesions, MDCT revealed three shrinkage
patterns: pattern 1a, concentric shrinkage without surrounding lesions;
pattern 1b, concentric shrinkage with surrounding lesions; and pattern 2,
shrinkage with residual multinodular lesions (Figs.
3A,
3B, and
3C). In cases that showed the
separated and mixed patterns of enhancement on CT before neoadjuvant
chemotherapy, concentric shrinkage of the index tumor with separated enhancing
lesions was identified as pattern 2. Pattern 1b was observed in only those
cases classified as showing the grouped lesion pattern on CT before
neoadjuvant chemotherapy.
View larger version (11K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A —Shrinkage patterns after neoadjuvant chemotherapy. In partial
response group with nonreplaced lesions, MDCT revealed pattern 1a (A),
concentric shrinkage without surrounding lesions; pattern 1b (B),
concentric shrinkage with surrounding lesions; and pattern 2 (C),
shrinkage with residual multinodular lesions.
|
|
View larger version (11K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B —Shrinkage patterns after neoadjuvant chemotherapy. In partial
response group with nonreplaced lesions, MDCT revealed pattern 1a (A),
concentric shrinkage without surrounding lesions; pattern 1b (B),
concentric shrinkage with surrounding lesions; and pattern 2 (C),
shrinkage with residual multinodular lesions.
|
|
View larger version (10K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3C —Shrinkage patterns after neoadjuvant chemotherapy. In partial
response group with nonreplaced lesions, MDCT revealed pattern 1a (A),
concentric shrinkage without surrounding lesions; pattern 1b (B),
concentric shrinkage with surrounding lesions; and pattern 2 (C),
shrinkage with residual multinodular lesions.
|
|
The CR group as assessed on MDCT included one case of pathologic CR, two
cases of DCIS, and one case of invasive cancer
(Table 2). Breast-conserving
surgery was performed in three patients and mastectomy in one. All cases
showed negative surgical margins.
Tables 4 and
5 show the relationship between
the tumor distribution on CT before neoadjuvant chemotherapy, the shrinkage
pattern in the PR group, and the histologic extent of the lesions. In pattern
1a, assessment of the tumor extent on MDCT and histology revealed a deviation
of less than 2 cm in diameter in 14 (88%) of 16 cases (Figs.
4A and
4B). CT images obtained after
neoadjuvant chemotherapy revealed two cases of false-negative lesions showing
the separated or mixed pattern of enhancement. These lesions were 2-mm DCIS
and 3-mm invasive foci corresponding to the enhancing regions on CT images
obtained before neoadjuvant chemotherapy (Figs.
5A and
5B). One of these was a case
of inflammatory cancer. In pattern 1b, the tumor extent was detected with
accuracy in three (100%) of three cases (Figs.
6A and
6B). In pattern 2, CT
underestimated the residual tumor extent by more than 2 cm in all five
patients (Figs. 7A and
7B), including three cases of
inflammatory cancer. There were four cases of inflammatory cancer in the PR
group with nonreplaced lesions that were underestimated by MDCT.
View this table:
[in this window]
[in a new window]
|
TABLE 4: Distribution and Shrinkage Pattern of Breast Tumors on MDCT in Cases of
Complete Response and Partial Response
|
|
View larger version (114K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4A —68-year-old woman with invasive ductal carcinoma of left breast
(solitary lesion: T3 N1). Early phase CT image acquired before neoadjuvant
chemotherapy shows localized enhancement in upper outer quadrant of left
breast.
|
|
View larger version (157K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B —68-year-old woman with invasive ductal carcinoma of left breast
(solitary lesion: T3 N1). Early phase CT image acquired after neoadjuvant
chemotherapy shows pattern 1a shrinkage. Histologic evaluation of lumpectomy
specimen revealed 2.5-cm invasive ductal carcinoma.
|
|
View larger version (156K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5A —45-year-old woman with inflammatory carcinoma of right breast
(separated lesion: T4d N1). Early phase CT image acquired before neoadjuvant
chemotherapy shows localized enhancing masses in lower inner quadrant
(long arrow) and outer region of right breast (short
arrow).
|
|
View larger version (128K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5B —45-year-old woman with inflammatory carcinoma of right breast
(separated lesion: T4d N1). Late phase CT image acquired after neoadjuvant
chemotherapy shows pattern 1a shrinkage. Histologic evaluation of mastectomy
specimen revealed 0.9-cm invasive ductal carcinoma (arrow) in lower
inner quadrant. False-negative lesions were 3-mm invasive foci in outer region
that corresponded to enhancing mass seen on CT performed before neoadjuvant
chemotherapy.
|
|
View larger version (157K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6A —44-year-old woman with invasive ductal carcinoma of left breast
(grouped lesion: T3 N0). Early phase CT image of left breast acquired before
neoadjuvant chemotherapy shows localized enhancing mass with surrounding
spotty enhancement in upper outer quadrant.
|
|
View larger version (142K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6B —44-year-old woman with invasive ductal carcinoma of left breast
(grouped lesion: T3 N0). Late phase CT image acquired after neoadjuvant
chemotherapy shows pattern 1b shrinkage. Histologic evaluation of lumpectomy
specimen revealed 3.5-cm invasive ductal carcinoma with surrounding invasive
and in situ ductal carcinoma.
|
|
View larger version (87K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7A —52-year-old woman with invasive ductal carcinoma of left breast
(solitary lesion: T3 N1). Early phase CT image of left breast acquired before
neoadjuvant chemotherapy shows localized enhancement in upper outer
quadrant.
|
|
View larger version (114K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7B —52-year-old woman with invasive ductal carcinoma of left breast
(solitary lesion: T3 N1). Late phase CT image acquired after neoadjuvant
chemotherapy shows pattern 2 shrinkage. Histologic evaluation of mastectomy
specimen revealed 5.5-cm invasive and in situ ductal carcinomas.
|
|
The mean ± SD of the difference between size estimates based on
histology and those based on MDCT was 1.1 ± 1.3 cm (range, 0-5.0 cm) in
pattern 1a shrinkage, 1.3 ± 0.79 cm (range, 0.4-1.9 cm) in pattern 1b
shrinkage, and 3.0 ± 1.2 cm (range, 2.2-5.1 cm) in pattern 2 shrinkage.
The difference between the MDCT measurement and histologic size was
significantly smaller (p < 0.01) in pattern 1 shrinkage compared
with pattern 2 shrinkage (Fig.
8).
Breast-Conserving Surgery
To set the criteria for the application of breast-conserving surgery in the
current study, those patients who exhibited CR or showed pattern la or 1b
shrinkage after chemotherapy were selected from those with solitary or grouped
lesions on CT images obtained before neoadjuvant chemotherapy CT.
Theoretically, 19 patients met these criteria. In reality, however, six who
desired a mastectomy were excluded and another patient (showing a mixed lesion
and pattern 1a shrinkage) who strongly wanted to have breast conservation was
added. Thus, a total of 14 patients underwent breast-conserving surgery. All
cases in which breast-conserving surgery was performed showed negative
surgical margins.
Discussion
One of the major objectives of neoadjuvant chemotherapy for breast cancer
is preoperative size reduction of the primary tumor. Having precise
information about residual tumor is crucial for breast-conserving surgery to
be successful. Several studies comparing the clinical and imaging assessments
of tumors treated with neoadjuvant chemotherapy have shown that MRI is
superior to both clinical examination and mammography for assessing tumor
response to neoadjuvant chemotherapy
[5,
6,
9,
11,
12]. On the other hand,
contrast-enhanced helical CT has been reported to be a highly accurate imaging
technique for the detection of breast cancer residua after neoadjuvant
chemotherapy [13,
14]. Recently, MDCT, which
enables faster scanning and allows higher resolution of the volume data than
single-detector helical CT, has become available. Inoue et al.
[17] reported that breast MDCT
was superior to mammography and sonography for both the detection of breast
tumors and the assessment of tumor extent.
Standardized protocols and guidelines for breast MRI or CT after
neoadjuvant chemotherapy have not yet been formulated. Furthermore, there are
no reports concerning appropriate interpretation of the results of these
dynamic studies, to our knowledge. We reported that early phase images
obtained by dynamic MDCT were useful for the assessment of tumor extent
[15]. In contrast, we found
that late phase images showed a better correlation with the extent of breast
cancer after neoadjuvant chemotherapy
[16]. Changes in tumor
vascularity in response to neoadjuvant chemotherapy may explain the gradually
enhancing pattern [8]. In
addition, Weatherall et al. [6]
reported that the accuracy of MRI after neoadjuvant chemotherapy might be
improved if a lower cutoff level of enhancement were accepted as abnormal.
Regarding the morphology of the breast cancer before neoadjuvant
chemotherapy, Partridge et al.
[8] found that diffuse lesions
as compared with localized tumors on MRI had extensions that were difficult to
measure and correlate with pathologic findings. Moyses et al.
[13] reported that the CT
pattern before neoadjuvant chemotherapy showed a good correlation with the
histopathologic findings. The results were excellent for round opacities, but
not satisfactory for diffuse, scattered, or multinodular lesions.
Akashi-Tanaka et al. [14] also
reported that localized tumors as compared with diffuse tumors visualized on
CT could be treated safely by breast-conserving surgery with a negative margin
status. However, breast cancer has a variable distribution pattern. Coronal
multiplanar reconstruction images obtained on breast MDCT were found to be
suitable for the evaluation of the variable distribution
[15].
In a previous study, a new category in the classification of tumor
distribution pattern by MDCT was proposed—namely,
"replaced," which was defined as diffuse contrast enhancement in
whole quadrants [16]. In
replaced lesions, the tumor size of the pathologic cancer residua was similar
to the original tumor bed despite good clinical response
[16]. Rosen et al.
[9] reported good clinical
response in similar cases, with innumerable small foci of residual invasive
carcinoma spread throughout the original tumor bed (total field of tumor) on
MRI.
In our study, all patients with tumors that showed the replaced lesion
pattern underwent mastectomy, and these lesions were characterized
histologically by the presence of numerous viable cells with fibrous tissue
spread throughout the original tumor bed. Areas of gradual enhancement
visualized on MDCT corresponded to the fibrous changes. However, late phase
images were excellent for the depiction of the actual disease extent. We
hypothesize that widespread fibrous changes occur in response to neoadjuvant
chemotherapy in the original tumor bed and that the innumerable foci of
residual cancer become included in the gradually enhancing fibrous lesions. In
the cases of replaced lesion as assessed on CT performed before neoadjuvant
chemotherapy, the indications for breast-conserving surgery must be
restrictive or intraoperative assessment of the surgical margins is mandatory
despite a good clinical response.
In this study, 11 cases of inflammatory cancer were included. There were
three in the NR group, four in the PR group with nonreplaced lesions, and four
in the PR group with replaced lesions. All these cases showed multifocal and
multicentric distribution in MDCT (grouped, one; separated, three; mixed, one;
replaced six). The tumor extent in all the cases of inflammatory cancer with
nonreplaced lesions was underestimated by MDCT. In the cases of inflammatory
cancers also, the indications for breast-conserving surgery must be also
restrictive despite a good clinical response.
Regarding the relationship between the shrinkage pattern in the PR group
and histologic extent, accurate detection of the tumor extent with a deviation
of less than 2 cm in length was obtained in 14 (88%) of the 16 cases with
pattern 1a. In those with pattern 1b, the tumor extent could be assessed
accurately in three (100%) of three cases. The two cases with false-negative
results included one case each with the separated and mixed pattern detected
on CT before neoadjuvant chemotherapy and one inflammatory cancer. In cases
showing shrinkage pattern 1a with a multicentric distribution on CT performed
before neoadjuvant chemotherapy, such as the separated and mixed pattern, the
frequency of successful breast conservation was 50% (2/4). Thus, the
indications for breast-conserving surgery must be carefully selected. In the
cases showing pattern 2, CT underestimated the residual tumor extent by more
than 2 cm in all five patients. Our results suggest that breast-conserving
surgery may be difficult in cases showing pattern 2 shrinkage.
A previous comparison of CT and MRI for assessing the extent of residual
breast cancer after neoadjuvant chemotherapy revealed that MRI may be more
advantageous than CT for detecting small invasive foci and DCIS
[16]. Recent studies reported
a high correlation between the MRI pattern and histology for the assessment of
residual malignancy after neoadjuvant chemotherapy
[6,
8,
9]. Partridge et al.
[8] explained that the
high-resolution technique (0.7 x 0.9 x 2 mm) with fat suppression
increased the sensitivity of detection of residual malignancy after
neoadjuvant chemotherapy. Nonetheless, MRI had an overall tendency to
overestimate tumor extent. Rosen et al.
[9] reported that the rate of
overestimation was 52% (11/21) even after reduction of the background breast
glandular activity after neoadjuvant chemotherapy.
In this study, MDCT had an overall tendency to underestimate tumor extent.
Compared with the correlation between the measurements based on a clinical
examination and histologic size, however, the correlation between the
measurements based on MDCT and histologic size was found to be more
significant (Table 3). Our
apparently higher success rate using MDCT as compared with that reported by
Rosen et al. [9] may be related
to two major factors: difference in histologic measurement technique (our
measurements were based on the largest diameter of not only the largest single
focus of invasive carcinoma, but also of in situ ductal carcinoma); and our
measurements were conducted in the coronal plane. The difference in tumor size
between that assessed on coronal multiplanar reconstruction images of MDCT and
by histologic examination is small because the histologic measurement is
conducted in a plane perpendicular to the plane of the histologic section.
In addition, before treatment of patients with locally advanced breast
cancer, evaluation of the clinical stage is necessary. CT and sonography are
usually performed for the detection of cervical, axillary, and mediastinal
lymph nodes and of lung and abdominal metastases at our institute. Many, if
not all, patients with locally advanced breast cancer undergo preoperative
evaluation for metastatic disease, often with MDCT. Therefore, unlike MRI,
obtaining tumor volume data with MDCT does not require an additional
examination. This may be not only an effective but also a cost-effective means
of assessing tumor volume. This is particularly true when comparing MDCT with
MRI, for which another examination would be necessary. In our results, there
was agreement between the MDCT assessment and pathologic assessment in 44
(94%) of 47 tumors. There were three false-negative cases: two cases of DCIS
(22 and 45 mm) and one case of scattered invasive foci over a diameter of 30
mm without mass formation. An additional breast MRI examination may be
conducted before surgery in cases with clinical CR and in cases with negative
MDCT findings after neoadjuvant chemotherapy. However, because the use of CT
in the diagnosis of breast disease is beset with the real problem of X-ray
exposure, further study in comparing these two techniques is necessary.
In conclusion, MDCT is useful for the assessment of residual cancer after
neoadjuvant chemotherapy. In particular, MDCT classification of the type of
tumor distribution before neoadjuvant chemotherapy and of the shrinkage
patterns after neoadjuvant chemotherapy is thought to be important in the
preoperative evaluation of breast-conserving surgery.
References
- Fisher B, Brown A, Mamounas E, et al. Effect of preoperative
chemotherapy on local-regional disease in women with operable breast cancer:
findings from National Surgical Adjuvant Breast and Bowel Project B-18.
J Clin Oncol 1997;15
: 2483-2493[Abstract/Free Full Text]
- Fisher B, Bryant J, Wolmark N, et al. Effect of preoperative
chemotherapy on the outcome of women with operable breast cancer. J
Clin Oncol 1998; 16:2672
-2685[Abstract]
- Mamounas EP, Fisher B. Preoperative (neoadjuvant) chemotherapy in
patients with breast cancer. Semin Oncol2001; 28:389
-399[CrossRef][Medline]
- Goldhirsch A, Glick JH, Gelber RD, Coates AS, Senn HJ. Meeting
highlights: international panel consensus on the treatment of primary breast
cancer. J Clin Oncol 2001;19
: 3817-3827[Free Full Text]
- Abraham DC, Jones RC, Jones SE, et al. Evaluation of neoadjuvant
chemotherapeutic response of locally advanced breast cancer by magnetic
resonance imaging. Cancer 1996;78
: 91-100[CrossRef][Medline]
- Weatherall PT, Evans GF, Metzger GJ, Saborrian MH, Leitch AM. MRI
vs. histologic measurement of breast cancer following chemotherapy: comparison
with x-ray mammography and palpation. J Magn Reson
Imaging 2001; 13:868
-875[CrossRef][Medline]
- Rieber A, Brambs HJ, Gabelmann A, Heilmann V, Kreienberg R, Kuhn T.
Breast MRI for monitoring response of primary breast cancer to neo-adjuvant
chemotherapy. Eur Radiol 2002;12
: 1711-1719[CrossRef][Medline]
- Partridge SC, Gibbs JE, Lu Y, Esserman LJ, Sudilovsky D, Hylton NM.
Accuracy of MR imaging for revealing residual breast cancer in patients who
have undergone neoadjuvant chemotherapy. AJR2002; 179:1193
-1199[Abstract/Free Full Text]
- Rosen EL, Blackwell KL, Baker JA, et al. Accuracy of MRI in the
detection of residual breast cancer after neoadjuvant chemotherapy.
AJR 2003; 181:1275
-1282[Abstract/Free Full Text]
- Wasser K, Sinn HP, Fink C, et al. Accuracy of tumor size
measurement in breast cancer using MRI is influenced by histological
regression induced by neoadjuvant chemotherapy. Eur
Radiol 2003; 13:1213
-1223[Medline]
- Londero V, Bazzocchi M, Del Frate C, et al. Locally advanced breast
cancer: comparison of mammography, sonography and MR imaging in evaluation of
residual disease in women receiving neoadjuvant chemotherapy. Eur
Radiol 2004; 14:1371
-1379[Medline]
- Warren RM, Bobrow LG, Earl HM, et al. Can breast MRI help in the
management of women with breast cancer treated by neoadjuvant chemotherapy?
Br J Cancer 2004;90
: 1349-1360[CrossRef][Medline]
- Moyses B, Haegele P, Rodier JF, et al. Assessment of response by
breast helical computed tomography to neoadjuvant chemotherapy in large
inflammatory breast cancer. Clin Breast Cancer2002; 2:304
-310[Medline]
- Akashi-Tanaka S, Fukutomi T, Sato N, et al. The use of
contrast-enhanced computed tomography before neoadjuvant chemotherapy to
identify patients likely to be treated safely with breast-conserving surgery.
Ann Surg 2004;239
: 238-243[CrossRef][Medline]
- Tozaki M, Kawakami M, Suzuki M, Uchida K, Yamashita A, Fukuda K.
Diagnosis of Tis/T1 breast cancer extent by multislice helical CT: a novel
classification of tumor distribution. Radiat Med2003; 21:187
-192[Medline]
- Tozaki M, Uno S, Kobayashi T, et al. Histologic breast cancer
extent after neoadjuvant chemotherapy: comparison with multidetector-row CT
and dynamic MRI. Radiat Med 2004;22
: 246-253[Medline]
- Inoue M, Sano T, Watai R, et al. Dynamic multidetector CT of breast
tumors: diagnostic features and comparison with conventional techniques.
AJR 2003; 181:679
-686[Abstract/Free Full Text]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
M. Tozaki and K. Fukuda
High-spatial-resolution MRI of non-masslike breast lesions: interpretation model based on BI-RADS MRI descriptors.
Am. J. Roentgenol.,
August 1, 2006;
187(2):
330 - 337.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
