|
RESULTS
Patient and tumor characteristics stratified by ALNM status
are presented in Table 1. A total of 919 patients were identified
with breast carcinomas < 1.0 cm. These included 199
patients (22.0%) with T1a tumors and 720 patients (78.0%) with
T1b tumors. The age of the patients ranged from 24 to 90 years
with a mean and median age of 57.5 years and 57.0 years, respectively.
ALNM was detected in 165 patients giving an overall incidence
of 18.0%. ALNM was detected in 32 patients with T1a and 133 patients
with T1b tumors, yielding an overall incidence of nodal disease
in 16.0% and 18.5%, respectively. The majority of patients were
Caucasian (95%). Infiltrating ductal carcinoma was the predominant
histologic type seen in 808 patients (88%), followed by infiltrating
lobular in 92 patients (10%). There were no differences in ALNM
among the different histologic types.
Table 1. Patient and Tumor Characteristics (n = 919)
|
|
Variable |
n |
Node-positive (n = 165) |
Node-negative (n = 754) |
|
|
Mean age (yr) ± SD: |
919 |
55.4 ± 11.3 |
58.0 ± 12.0 |
|
Age groups (yr)* |
|
|
|
< 30
30-39
40-49
50-59
60-69
> 70 |
6
74
195
267
233
164 |
0%
30%
18%
20%
18%
12% |
100%
70%
82%
80%
82%
82% |
|
Tumor diameter (cm)† |
|
|
|
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00 |
21
21
22
40
95
56
89
135
99
341 |
10%
5%
14%
15%
21%
7%
15%
18%
15%
23% |
90%
95%
86%
85%
79%
93%
85%
82%
85%
77% |
|
Tumor grade‡ |
|
|
|
1
2
3 |
205
240
76 |
13%
16%
29% |
87%
84%
71% |
|
Lymphatic invasion§ |
|
|
|
Yes
No |
28
450 |
50%
15% |
50%
85% |
|
Palpable mass|| |
|
|
|
Yes
No |
250
103 |
19%
12% |
81%
88% |
|
ER + status¶ |
|
|
|
Yes
No |
337
86 |
17%
23% |
83%
77% |
|
PR + status# |
|
|
|
Yes
No |
276
139 |
17%
19% |
83%
81% |
|
*p = 0.04 by chi-square test for trend.
†p = 0.01 by chi-square test for trend.
‡p = 0.01 by chi-square test for trend (unknown, n = 398).
§p > 0.0001 by Fisher's exact test (unknown, n = 441).
||p = 0.10 by chi-square test (unknown, n = 566).
¶p = 0.17 by chi-square test (unknown, n = 496).
#p = 0.61 by chi-square test (unknown, n = 504).
The univariate relationship between clinical and pathologic
variables and ALNM status is presented in Table 2. Four variables
were found to be significant in univariate analysis. These included:
increasing size of the tumor, poor histologic grade, the presence
of lymphatic or vascular invasion, and younger age of the patient.
Increasing size of the tumor was significantly associated with
an increased risk of ALNM and was demonstrated for each 1-mm
increase in size (OR = 2.66, 95% CI = 1.28 to 5.75; p = 0.01).
Increasing or poorer histologic grade was significantly associated
with nodal disease (OR = 2.69, p = 0.003). Patients with ALNM
were more likely to have a tumor grade of 3 (25.0% ALNM versus
12.5% node-negative, p = 0.004). The presence of lymphatic or
vascular invasion was also a significant factor for ALNM (OR
= 5.52, p = 0.0001), with 17.0% of patients with ALNM having
positive invasion compared with only 3.5% in node-negative patients
(p < 0.0001).
Table 2. Univariate Analysis of Factors Associated with
Axillary Lymph Node Metastases (n = 919)
|
|
Factor |
Unadjusted odds ratio and 95% confidence interval |
p Value |
|
|
Age (yr)* |
|
|
< 50
> 50 |
1.00 (referent)
0.98 (0.96, 0.99) |
0.01 |
|
Tumor diameter (cm)† |
2.66 (1.28, 5.75) |
0.01 |
|
Tumor grade‡ |
|
|
1
2
3 |
1.00 (referent)
1.28 (0.76, 2.19)
2.69 (1.41, 5.10) |
0.36
0.003 |
|
Lymphatic invasion§ |
|
|
No
Yes |
1.00 (referent)
5.52 (2.51, 12.19) |
0.0001 |
|
Palpable mass|| |
|
|
No
Yes |
1.00 (referent)
1.76 (0.92, 3.61) |
0.10 |
|
ER+ status¶ |
|
|
No
Yes |
1.00 (referent)
0.67 (0.38, 1.22) |
0.17 |
|
PR+ status# |
|
|
No
Yes |
1.00 (referent)
0.87 (0.52, 1.49) |
0.61 |
|
*Treated as a continuous variable (for each
1 year increase).
†Treated as a continuous variable (for each 0.10-cm increase).
‡Unknown, n = 398.
§Unknown, n = 441.
||Unknown, n = 566.
¶Unknown, n = 496.
#Unknown, n = 504.
Additional multivariate logistic regression was performed
on those variables found to be statistically significant in univariate
analysis. We were unable to include lymphatic and vascular invasion
as a factor in the multivariate analysis because of insufficient
data to support the final model. The relationship among the three
remaining clinical and pathologic factors and ALNM status are
presented in Table 3. Again, increasing tumor size (adjusted
OR = 3.58, p = 0.03), poor histologic grade (adjusted OR = 2.45,
p = 0.01), and younger age (adjusted OR = 0.61, p = 0.05) were
all significant independent factors for ALNM.
Table 3. Multivariate Analysis of Factors Associated with
Axillary Lymph Node Metastases (n = 919)
|
|
Factor |
Adjusted odds ratio and 95% confidence interval |
p Value |
|
|
Age (yr)† |
|
|
< 50
> 50 |
1.00 (referent)
0.61 (0.37, 1.02) |
0.05 |
|
Tumor diameter (cm)‡ |
3.58 (1.18, 11.89) |
0.03 |
|
Tumor grade |
|
|
1
2
3 |
1.00 (referent)
1.26 (0.74, 2.17)
2.45 (1.27, 4.68) |
0.40
0.01 |
|
*Adjusted for all other variables in a logistic
regression model
†Treated as a continuous variable (for each 1 year increase).
‡Treated as a continuous variable (for each 0.10-cm increase).
§Unknown, n = 398.
When four of the favorable clinical and pathologic parameters
were analyzed, that is, in patients 50 years of age or older
with T1a (< 5-mm) tumors that were well-differentiated
and lacked lymphatic or vascular invasion, a total of 108 patients
were identified. With all the favorable factors taken into account,
14 patients (13%) were still identified as having ALNM. When
age increased to more than 60 years and all other parameters
remained the same, 6 of 69 patients (8.7%) had ALNM.
Introduction
| Methods
| Results | Discussion
| References
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