Patient Characteristics
In this study 172 patients with T0-4, cN1-3, M0 breast cancer were enrolled, including one bilateral breast cancer, a total of 173 axillae. The median age of the patients was 51 years old, ranged from 25 to 76. Of these, 163(94.2%) patients were invasive breast cancer. Eleven(6.4%) of the 173 had T1 tumors and 162(93.6%) had T2-4 tumors. Tumors were hormone receptor-positive in 68.2% of cases, HER2-positive in 30.1%, and 90.2% showed a Ki-67 index >14%(Table 1).
The number of NAC cycles less than or equal to 2 was 31 cases (17.9%) ,meanwhile, 142 cases (82.1%) received more than 2 NAC cycles. During the postoperative evaluation,the number of pathological complete response (PCR) was 8 cases (4.6%), the number of partial response (Pr) was 89 cases (51.4%), the number of progressive disease (PD) was 7 cases (4.0%), and the number of stable disease (SD) was 67 cases (38.7%) .PCR and PR were regarded as effective for chemotherapy, and the effective rate of NAC was 56.0%. All of the patients’ characteristics are listed in Table 1.
Table 1. Baseline characteristics.
Parameter
|
N
|
N(%)
|
Age
|
|
|
≤50
|
86
|
49.7
|
>50
|
87
|
50.3
|
Tumor histology
|
|
|
Invasive breast cancer
|
163
|
94.2
|
DCIS
|
2
|
1.2
|
Not available
|
8
|
4.6
|
Clinical T category at diagnosis
|
Tis(carcinoma in situ)
|
2
|
1.2
|
T1
|
9
|
5.2
|
T2
|
107
|
61.8
|
T3
|
49
|
27.8
|
T4
|
6
|
4.0
|
cN(Clinical staging of lymph nodes)
|
cN1
|
97
|
56.1
|
cN2
|
1
|
0.6
|
cN3
|
75
|
43.4
|
TNM stage
|
|
|
ⅡA
|
5
|
2.9
|
ⅡB
|
61
|
35.3
|
ⅢA
|
29
|
16.9
|
ⅢB
|
2
|
1.2
|
ⅢC
|
75
|
43.4
|
Not available
|
1
|
0.6
|
Hormone receptor(HR) status
|
Negative
|
50
|
28.9
|
Positive
|
118
|
68.2
|
Not available
|
5
|
2.9
|
HER2 status
|
|
|
Negative
|
69
|
39.9
|
Positive
|
52
|
30.1
|
Not available
|
52
|
30.0
|
Ki-67 index
|
|
|
<14%
|
10
|
5.8
|
≥14%
|
156
|
90.2
|
Not available
|
7
|
4.0
|
IHC classification
|
Luminal
|
112
|
64.7
|
Her-2(+)
|
24
|
13.9
|
TNBC
|
21
|
12.1
|
Not available
|
16
|
9.3
|
Physical examination of axilla after NAC
|
Palpable
|
37
|
21.4
|
No palpable adenopathy
|
136
|
78.6
|
No. of chemotherapy cycles
|
<4
|
78
|
45.1
|
≥4
|
95
|
54.9
|
Association of Postchemotherapy AUS Findings With Pathologic Findings
After completion of neoadjuvant chemotherapy and within 4 weeks before surgery, all patients underwent an AUS to assess the morphologic appearance of the axillary lymph nodes. Lymph nodes were classified as normal if the radiologist was unable to visualize any lymph nodes on AUS or indicated that the lymph nodes were normal in morphologic appearance. Of 173 patients with postchemotherapy AUS results, 65(37.6%) had lymph nodes classified as normal on AUS, and 108(62.4%) had suspicious lymph nodes. Postchemotherapy AUS status was associated with nodal pathologic findings. Of the 65 patients with normal nodes as assessed by AUS, 42 patients (64.6%) were node positive on final pathology. In comparison, 95 (90.0%) of 108 patients who had suspicious nodes identified by AUS were found to have residual node-positive disease. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of postchemotherapy AUS for assessing axillary metastases were 69.3%, 63.9%, 88.0%, 35.4%, and 68.2%, respectively (Table 2). The ROC curve was plotted.
The ROC showed that the area under the curve(AUC) was 0.703(P=0.000,95%CI[0.605,0.800]), with a high statistical significance.
Table 2. Comparison of AUS and pathology after NAC
AUS
|
Pathological metastasis
|
|
Positive
|
Negative
|
Positive
|
95
|
13
|
Negative
|
42
|
23
|
|
Sensitivity
|
69.3%
|
|
|
Specificity
|
63.9%
|
|
|
Positive predictive value
|
88.0%
|
|
|
Negative predictive value
|
35.4%
|
|
|
Accuracy
|
68.2%
|
|
[Figure]
Table 3 lists tumor, patient and treatment characteristics for patients with normal lymph nodes as assessed by postchemotherapy AUS and for patients with suspicious lymph nodes. Physical examination of axilla after NAC, number of Chemotherapy cycles, Primary tumor reduction rate, Tumor status after NAC, ALN short axis after NAC and number of positive nodes differed significantly between patients with normal lymph nodes and those with suspicious nodes as assessed by AUS. Patients with suspicious nodal status based on AUS were also more likely to have a greater number of positive ALN than patients with normal AUS findings (56.5% v 20.0%, respectively, with four or more positive ALM; P<0.001). Patients with suspicious lymph nodes by AUS were also more likely to have residual invasive disease in the breast (pathologic T2 or greater) than T1/T0 disease compared with patients with normal AUS findings (75.9% v 23.1%, respectively; P=0.001).
Table 3.AUS after NAC was compared in each group
Characteristic
|
AUS after NAC(—)
|
|
|
AUS after NAC (+)
|
|
N
|
%
|
|
|
N
|
%
|
P
|
Nodal category before NAC
|
|
|
0.010
|
cN1-2
|
45
|
69.2
|
|
|
53
|
49.1
|
|
cN3
|
20
|
30.8
|
|
|
55
|
50.9
|
|
Physical examination of axilla after NAC
|
|
|
0.000
|
Negative
|
62
|
95.4
|
|
|
74
|
68.5
|
|
Positive
|
3
|
4.6
|
|
|
34
|
31.5
|
|
No. of Chemotherapy cycles
|
|
|
|
|
0.047
|
<4
|
23
|
35.4
|
|
|
55
|
50.9
|
|
≥4
|
42
|
64.6
|
|
|
53
|
49.1
|
|
Primary tumor reduction rate
|
|
|
0.004
|
<30%
|
19
|
29.2
|
|
|
56
|
51.9
|
|
≥30%
|
45
|
69.2
|
|
|
51
|
47.2
|
|
Tumor status after NAC
|
|
|
0.001
|
T<2.0cm
|
30
|
46.2
|
|
|
25
|
23.1
|
|
T≥2.0cm
|
34
|
52.3
|
|
|
82
|
75.9
|
|
ALN short axis after NAC
|
|
|
0.000
|
<10mm
|
63
|
96.9
|
|
|
69
|
63.9
|
|
≥10mm
|
2
|
3.1
|
|
|
39
|
36.1
|
|
No. of positive nodes
|
|
|
|
|
|
|
0.000
|
0-3
|
52
|
80.0
|
|
|
47
|
43.5
|
|
≥4
|
13
|
20.0
|
|
|
61
|
56.5
|
|
|
|
|
|
|
|
|
|
|
Single-factor and multiple-factor analysis of AUS after NAC
In single-factor analysis, we found that short axis of primary ALN, PR, HR, tumor size after NAC, tumor reduction rate, short axis of ALN after NAC, physical examination of axilla after NAC made a difference in FNR of AUS after NAC which hade statistically significant.And the results of the other subgroups were not statistically significant,all P values were greater than 0.05.
FNR of AUS was 17.6% in the subgroup with ≥4ALNs metastasis (pN2-3), while FNR of AUS in the subgroup with no metastasis or < 4 ALNs metastasis (pN0-1) was 46.0% .The difference was significant (P=0.000).After NAC, 37 cases were clinically touched by enlarged lymph nodes, 34 cases of which were pathologically confirmed by lymph node metastasis, 3 cases of which was diagnosed as negative by AUS. FNR of AUS in this part of cases was 8.8%, which was far lower than 37.9% (P=0.001) of the non-touched lymph nodes.
FNR diagnosed by AUS in the tumor T≥ 2.0cm subgroup after NAC was 25%, far lower than 47.2% in the primary focus group T<2.0cm.In the subgroup of primary focus reduction rate <30%,FNRwas 19.7%, far lower than 41.4% in the PD group (the primary focus reduction rate ≥ 30%), and the difference was significant (P=0.006).
Further multiple-factor analysis was performed for the above results, independent factors associated with the AUS after NAC FNR is: after NAC ALN short diameter and pN in installment, the NAC ALN after short diameter on the judgement of the state of AUS after NAC significance is bigger (OR = 7.021), the FNR AUS after NAC ALN short diameter 10 mm OR the group of less than 10% (5.4%), short diameter < 10 mm in the two groups were greater than 10%.All the above data is listed in Table4 and Table5.
Table 4. FNR of AUS after NAC in 137 cases of ALNs positive in different subgroups
Characteristics
|
P(+)
|
US(+)
n
|
US(-)
|
χ2
|
P
|
Logistic
|
n
|
FNR(%)
|
P
|
Age
|
|
|
|
|
3.12
|
0.077
|
|
≤50
|
66
|
41
|
25
|
37.9
|
|
|
|
>50
|
71
|
54
|
17
|
23.9
|
|
|
|
Clinical T category at diagnosis
|
|
|
|
|
1.293
|
0.256
|
|
Tis、T1-2
|
91
|
66
|
25
|
27.5
|
|
|
|
T3-4
|
46
|
29
|
17
|
37.0
|
|
|
|
Nodal category(axillary ultrasound)
|
|
|
|
|
2.945
|
0.086
|
|
cN1-2
|
73
|
46
|
27
|
37.0
|
|
|
|
cN3
|
64
|
49
|
15
|
23.4
|
|
|
|
Primary ALN short axis
|
|
|
|
|
11.408
|
0.001
|
0.183
|
<1cm
|
44
|
22
|
22
|
50.0
|
|
|
|
≥1cm
|
93
|
73
|
20
|
21.5
|
|
|
|
Primary TNM stage
|
|
|
|
|
1.293
|
0.256
|
|
Ⅱ
|
46
|
29
|
17
|
37.0
|
|
|
|
Ⅲ
|
91
|
66
|
25
|
27.5
|
|
|
|
ER(estrogen receptor)
|
|
|
|
|
0.610
|
0.435
|
|
Negative
|
43
|
32
|
11
|
25.6
|
|
|
|
Positive
|
90
|
61
|
29
|
32.2
|
|
|
|
PR(progesterone receptor)
|
|
|
|
|
5.057
|
0.025
|
0.540
|
Negative
|
49
|
40
|
9
|
18.4
|
|
|
|
Positive
|
84
|
53
|
31
|
36.9
|
|
|
|
HR
|
|
|
|
|
4.220
|
0.040
|
0.931
|
Negative
|
36
|
30
|
6
|
16.7
|
|
|
|
Positive
|
97
|
63
|
34
|
35.1
|
|
|
|
Her-2(Human epidermal growth factor receptor-2)
|
|
|
|
|
1.058
|
0.589
|
|
Negative
|
59
|
43
|
16
|
27.1
|
|
|
|
Positive
|
34
|
24
|
10
|
29.4
|
|
|
|
Ki-67
|
|
|
|
|
0.195
|
0.659
|
|
≤14%
|
8
|
5
|
3
|
37.5
|
|
|
|
>14%
|
123
|
86
|
37
|
30.1
|
|
|
|
Immunohistochemistry classification
|
|
|
|
|
3.21
|
0.201
|
|
Luminal
|
93
|
61
|
32
|
34.4
|
|
|
|
Her-2(+)
|
15
|
11
|
4
|
26.7
|
|
|
|
TNBC
|
16
|
14
|
2
|
12.5
|
|
|
|
Physical examination of axilla after NAC
|
|
|
|
|
10.141
|
0.001
|
0.427
|
Negative
|
103
|
64
|
39
|
37.9
|
|
|
|
Positive
|
34
|
31
|
3
|
8.8
|
|
|
|
Chemotherapy cycles
|
|
|
|
|
1.366
|
0.243
|
|
<4
|
69
|
51
|
18
|
26.1
|
|
|
|
≥4
|
68
|
44
|
24
|
35.3
|
|
|
|
Tumor reduction rate
|
|
|
|
|
7.516
|
0.006
|
0.559
|
<30%
|
66
|
53
|
13
|
19.7
|
|
|
|
≥30%
|
70
|
41
|
29
|
41.4
|
|
|
|
Tumor status after NAC
|
|
|
|
|
6.124
|
0.013
|
0.113
|
T0-1
|
36
|
19
|
17
|
47.2
|
|
|
|
T2-4
|
100
|
75
|
25
|
25.0
|
|
|
|
ALN short axis after NAC
|
|
|
|
|
28.453
|
0.000
|
0.019
|
<5mm
|
19
|
5
|
14
|
73.7
|
|
|
|
≥5mm,<10mm
|
79
|
53
|
26
|
32.9
|
|
|
|
≥10mm
|
37
|
35
|
2
|
5.4
|
|
|
|
ALN long-to-short axis ratio after NAC
|
|
|
|
|
1.872
|
0.171
|
|
<2
|
76
|
59
|
17
|
22.4
|
|
|
|
≥2
|
51
|
34
|
17
|
33.3
|
|
|
|
pN(Pathological stage of lymph node)
|
|
|
|
|
12.969
|
0.000
|
0.004
|
pN0-1
|
63
|
34
|
29
|
46.0
|
|
|
|
pN2-3
|
74
|
61
|
13
|
17.6
|
|
|
|
Table 5. Logistic results of AUS after NAC in 137 cases of ALNs positive in different subgroups
|
Regression coefficient
|
Standard error
|
Wald
|
P
|
OR
|
95%CI of OR
|
short axis of ALN after NAC
|
1.949
|
0.831
|
5.502
|
0.019
|
7.021
|
1.378~35.776
|
pN
|
1.392
|
0.485
|
8.239
|
0.004
|
4.024
|
1.555~10.411
|
constant
|
-0.737
|
0.928
|
0.630
|
|
|
|