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Original Scientific Article
Predictive Factors Associated with Axillary Lymph Node
Metastases in T1a and T1b Breast Carcinomas: Analysis in More
Than 900 Patients
David E Rivadeneira, MD, Rache M Simmons, MD, FACS, Paul J
Christos, MPH, Kayane Hanna, BS, John M Daly, MD, FACS, Michael
P Osborne, MD, FACS
Background: Axillary lymph node metastasis (ALNM) represents
the single most important prognostic indicator in patients diagnosed
with breast cancer. The proportion of < 1-cm (T1a,
T1b) invasive breast carcinomas is increasing. The incidence
and predictive factors associated with ALNM in patients with
< 1-cm tumors remains unclear and the role of axillary
lymph node dissection in these patients has been questioned.
The purpose of this study was to determine clinical and pathologic
factors predictive of ALNM in patients with < 1-cm
invasive breast carcinomas by univariate and multivariate analyses.
Study Design: Review analysis from a prospective database
identified patients with < 1-cm invasive breast cancers
treated at our institution between 1990 and 1996. All patients
underwent a resection of the primary tumor and axillary lymph
node dissections. Routine patient and tumor characteristics evaluated
included: age, race, tumor size, histologic grade, estrogen and
progesterone receptor status, and lymphatic and vascular invasion.
Univariate and multivariate analyses were performed. Adjusted
odds ratios (OR) and 95% confidence intervals (CI) are presented.
Results: A total of 919 patients were identified in
this study with tumors < 1 cm. These included 199 patients
(21.7%) with T1a tumors and 720 patients (78.3%) with T1b tumors.
ALNM was detected in 165 patients with an overall incidence of
18.0%. Of the ALNM group, 32 patients (19.4%) had T1a tumors
and 133 patients (80.6%) had T1b tumors. Four variables were
found to be significant in univariate analysis. These included:
increasing tumor size, poor histologic grade, presence of lymphatic
or vascular invasion, and younger age of the patient. An increase
in tumor size was associated with a significant risk of ALNM
(OR = 2.66, 95% CI = 1.28 to 5.75; p = 0.01). Poor tumor grade
and the presence of lymphatic or vascular invasion were also
associated with an increased risk of ALNM (OR = 2.69, p = 0.003
and OR = 5.52, p = 0.0001, respectively). Patients with ALNM
were more likely to have a tumor grade of 3 (25.0% ALNM versus
12.5% node-negative, p = 0.004) and lymphatic or vascular invasion
(16.9% ALNM versus 3.5% node-negative, p < 0.0001). In multivariate
analysis, an increased risk of ALNM was demonstrated with increasing
tumor size (0.1-cm increments), poor histologic grade, and younger
age.
Conclusions: This study investigated clinical and pathologic
factors influencing ALNM in patients with T1a and T1b breast
carcinomas. We have identified three factors by multivariate
analysis as significant independent predictors of ALNM in this
group of patients. These include increasing tumor size, poor
histologic grade, and younger age. Given the significant amount
of ALNM demonstrated in this study (overall 18%) and the inability
to identify a subgroup of patients that had an acceptable low
risk of ALNM, the complete omission of assessing the axilla for
metastatic disease in patients with small breast cancers cannot
be advocated. Our recommendation for patients diagnosed with
T1a and T1b tumors is to have their axilla investigated for metastatic
disease either by traditional axillary lymph node dissections
or by intraoperative lymphatic mapping and sentinel lymph node
biopsy techniques.
References
Introduction
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