Clinical Investigation
Predicting Likelihood of Having Four or More Positive Nodes in Patient With Sentinel Lymph Node-Positive Breast Cancer: A Nomogram Validation Study

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Purpose

Katz suggested a nomogram for predicting having four or more positive nodes in sentinel lymph node (SLN)-positive breast cancer patients. The findings from this formula might influence adjuvant radiotherapy decisions. Our goal was to validate the accuracy of the Katz nomogram.

Methods and Materials

We reviewed the records of 309 patients with breast cancer who had undergone completion axillary lymph node dissection. The factors associated with the likelihood of having four or more positive axillary nodes were evaluated in patients with one to three positive SLNs. The nomogram developed by Katz was applied to our data set. The area under the curve of the corresponding receiver operating characteristics curve was calculated for the nomogram.

Results

Of the 309 patients, 80 (25.9%) had four or more positive axillary lymph nodes. On multivariate analysis, the number of positive SLNs (p < .0001), overall metastasis size (p = .019), primary tumor size (p = .0001), and extracapsular extension (p = .01) were significant factors predicting for four or more positive nodes. For patients with <5% probability, 90.3% had fewer than four positive nodes and 9.7% had four or more positive nodes. The negative predictive value was 91.7%, and sensitivity was 80%. The nomogram was accurate and discriminating (area under the curve, .801).

Conclusion

The probability of four or more involved nodes is significantly greater in patients who have an increased number of positive SLNs, increased overall metastasis size, increased tumor size, and extracapsular extension. The Katz nomogram was validated in our patients. This nomogram will be helpful to clinicians making adjuvant treatment recommendations to their patients.

Introduction

The rationale for performing axillary lymph node dissection (ALND) includes staging, improving regional control, predicting prognosis, and determining optimal adjuvant therapy 1, 2. At present, sentinel lymph node (SLN) biopsy is accepted as the standard approach for clinically node negative breast cancer (BC) patients (3). Completion axillary lymph node dissection (CALND) is performed if the SLN is positive. For various reasons, a subset of patients will not have undergone CALND, and additional therapeutic decisions must be made according to the SLN results. Parameters such as lymphovascular invasion (LVI), number of positive SLNs, overall metastasis size (OMS), and presence of extracapsular extension (ECE) have been evaluated to predict for the probability of residual disease in the axilla in SLN-positive patients 4, 5, 6, 7. Although systemic therapy decisions might not be influenced by the finding of additional nodal disease, the extent of adjuvant radiotherapy could be affected if four or more axillary nodes are positive. Patients with four or more positive axillary nodes have a greater risk of regional nodal failure and will benefit from the additional radiotherapy to the axillary apex and supraclavicular fossa 8, 9, 10, 11, 12. Katz et al.(13) developed a nomogram for predicting the presence of four or more involved axillary nodes for SLN-positive BC patients. It seeks to help in identifying patients with a low probability of having four or more nodes using the known pathologic features of their primary tumor and SLNs. The purpose of this study was to validate the accuracy of the Katz nomogram in BC patients with a positive SLN in our institution.

Section snippets

Methods and Materials

We reviewed the information from the tumor registry database of patients who had undergone SLN mapping for BC between 1999 and 2007 at the Magee-Womens Hospital of the University of Pittsburgh Medical Center. A total of 309 patients with invasive BC, who had undergone SLN biopsy and CALND, were identified. Those patients with more than three positive SLNs were excluded. We excluded patients with fewer than six retrieved nodes in the axillary specimen because six nodes is the accepted minimal

Results

The patient and tumor characteristics are listed in Table 1. The median patient age was 54.3 years (range, 30–84). The mean tumor size was 2.18 cm (range, 0.2–8). Breast-conserving surgery was performed in 201 patients (65.1%). The histologic type was invasive ductal carcinoma in 267 (86.4%) and invasive lobular carcinoma in 42 (13.6%). Of the 309 patients, 152 (49.2%) had LVI surrounding the primary tumor. Twenty-one patients (6.7%) were negative for ER, PR, and Her2/neu. The micrometastasis

Discussion

The current standard of care for patients with a positive SLN is completion of Level 1 and 2 ALND. Nevertheless, ALND has several complications, including intercostal brachial nerve injury and upper extremity lymphedema. Accurate estimates of the likelihood of additional disease in the axilla can assist in decision-making about additional treatment. Scoring systems are useful and provide additional information for BC patients who decline CALND or who have medical comorbidities prohibiting

Conclusion

The results of our study have demonstrated that the Katz nomogram provides fairly accurate predictions for identifying patients with a low or high risk of four or more involved axillary lymph nodes in SLN-positive patients. Our findings have validated the Katz nomogram. This model should be tested and verified in additional, large, patient populations before it is widely accepted. Although nomograms developed at outside institutions should be used with caution when counseling patients regarding

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    Accepted as a poster presentation at San Antonio Breast Cancer Symposium 2008.

    Conflict of interest: none.

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