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ORIGINAL ARTICLES |
5 cm) Invasive Breast Cancer
From the Joyce Eisenberg Keefer Breast Center, John Wayne Cancer Institute at Saint Johns Health Center, Santa Monica, California.
Correspondence: Address correspondence and reprint requests to: Armando E. Giuliano, MD, John Wayne Cancer Institute, 2200 Santa Monica Boulevard, Santa Monica, CA 90404; Fax: 310-998-3995.
| ABSTRACT |
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5 cm) breast cancers and clinically negative axillae.
Methods: A prospectively entered database was used to identify all patients who underwent surgical management of histopathologically confirmed primary breast carcinomas
5 cm in diameter between September 1991 and August 2000. Patients who had clinically negative axillae and underwent SLND followed by completion axillary lymph node dissection (ALND) were selected for the study. The positivity rate, accuracy rate, and false-negative rate of SLND were determined.
Results: Of the 41 patients selected for the study, 24 had infiltrating ductal carcinoma and 17 had infiltrating lobular carcinoma. Mean tumor size was 7.12 cm (range, 523 cm). At least one sentinel lymph node (SLN) was identified in all cases. Thirty patients had tumor-positive SLNs. Axillary metastasis was also identified in one patient who did not have a positive SLN. Thus, SLN status accurately predicted regional nodal status in 98% (40 of 41) of cases. The false-negative rate of SLND was 3% (1 of 31). None of the three patients with SLN micrometastasis, defined as a tumor focus
2 mm, had tumor deposits in nonsentinel axillary lymph nodes. Only SLN macrometastasis (>2-mm tumor deposit) and primary tumor size
7 cm predicted nonsentinel axillary metastasis with significance on multivariate analysis (P = .008 and P = .046, respectively).
Conclusions: SLND is feasible and accurate in patients with large breast cancers and clinically negative axillae. Axillary lymph node dissection can be avoided in nearly one third of patients by focused examination of the SLN.
Key Words: Sentinel lymph node dissection Breast carcinoma Axillary staging Neoadjuvant chemotherapy
| INTRODUCTION |
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Complete axillary lymph node dissection (ALND) allows accurate axillary staging, but its potential complications are not insignificant.7 Because large breast cancers are usually diagnosed via fine-needle aspiration (FNA) or core-needle biopsy, a surgically moderate staging approach for the axilla would allow both diagnosis and staging to be completed in an ambulatory setting.
During the last decade, sentinel lymph node dissection (SLND) has gained rapid acceptance as a minimally invasive way of accurately assessing the axillary nodal status in patients with breast cancer.810 Although SLND is an excellent staging modality for small, early-stage breast cancers, its role for large breast cancers is controversial.11 We undertook this study to investigate the feasibility of SLND in patients with large (
5 cm) invasive breast cancers and determine its accuracy in predicting the status of the entire nodal basin. We hypothesized that use of SLND might eliminate the need for ALND in certain patients with clinically negative axillae.
| MATERIALS AND METHODS |
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5 cm in diameter between September 1991 and August 2000. Inclusion criteria were age
18 years, histopathologic evidence of invasive breast cancer
5 cm in greatest diameter, and clinically normal axillae. Exclusion criteria were pregnancy, hypersensitivity to vital blue dye (LymphazurinTM, US Surgical Corp., Norwalk, CT) from previous exposure, history of axillary surgery, inflammatory cancer, chest wall involvement, and clinical or radiographical evidence of American Joint Committee on Cancer (AJCC) stage III or IV disease. All patients signed informed consent approved by our institutional review board. After induction of general anesthesia or local anesthesia with intravenous sedation, intraoperative lymphatic mapping with blue dye was performed on all patients as previously described.8,12 Briefly, 3 to 5 ml of 1% Lymphazurin was injected peritumorally. Gentle massage of the breast for 3 to 5 minutes promoted passage of dye along the lymphatics. A small transverse skin incision was made over the axilla, and meticulous dissection was performed to visually identify the blue-stained lymphatic channels. These channels were followed proximally and distally to identify the blue-stained lymph nodes. Sentinel lymph nodes (SLNs) were defined as blue-stained lymph nodes reached by an afferent blue-stained lymphatic channel. Careful visual and manual exploration for several centimeters around each SLN identified any additional SLNs. After all SLNs had been removed, level I and II ALND was performed. Mastectomy or breast-conserving surgery was performed on the basis of the patients wishes and on technical and cosmetic feasibility.
The size of the primary tumor as measured on histopathologic sectioning was recorded according to AJCC staging criteria.13 Estrogen receptor status, progesterone receptor status, and HER-2/neu expression were evaluated as tumor-associated indicators of prognosis. Each patients clinical characteristics, tumor histology, and axillary status were recorded prospectively.
Pathologic Evaluation
Each SLN was processed routinely for permanent section with hematoxylin and eosin staining (H&E). If no tumor was identified, immunohistochemical staining (IHC) with a cytokeratin-binding antibody cocktail (MAK-6TM, Ciba-Corning, Alameda, CA) was performed. IHC-positive stains were confirmed by reinspection with H&E. Nonsentinel nodes (from the ALND specimen) were processed by routine pathologic techniques and examined only with H&E. A micrometastasis was defined as a tumor deposit
2 mm. If an SLN contained multiple tumor deposits, the sum of the diameters of these deposits was used to classify the metastasis as a micro- or macrometastasis. Primary tumor specimens were evaluated by routine histology.
Statistics
All data were reviewed and analyzed by the JWCIs Biostatistical Unit. Logistic regression analysis was used to estimate the risk of nonsentinel axillary lymph node metastasis on the basis of the patients age, menopausal status, and personal and family history of breast cancer; the primary tumors size, histology, and receptor status; and the SLNs tumor status. Statistical significance corresponded to a P value <.05.
| RESULTS |
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10 cm in diameter; the largest was 23 cm. Of the 39 patients who did not receive neoadjuvant chemotherapy, 31 had operable tumors that were <5 cm in diameter on clinical examination before definitive surgery, and 8 refused therapy.
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Incidence of Axillary Metastases
The average number of axillary lymph nodes removed was 17.2 (range, 737). The mean number of positive axillary lymph nodes was 4.5 (range, 121). Thirty-one patients (76%) had axillary metastases: 7 patients had one positive node, 8 patients had two or three positive nodes, and 16 patients had more than three positive axillary nodes.
At least one SLN was identified in all 41 patients. The average number of SLNs identified per patient was 1.6 (median, 1; range, 16). The median number of tumor-positive SLNs per patient was 1. Of the 30 patients (73%) with SLN metastases, 10 had tumor-free nonsentinel axillary nodes by H&E. Because 31 patients had axillary metastases, the false-negative rate of SLND was 3% (1 of 31), and SLN status accurately predicted regional nodal status in 98% (40 of 41) of cases. None of the three patients with SLN micrometastases had tumor in nonsentinel axillary nodes.
Predictors of Nonsentinel Axillary Node Metastasis
Table 2 lists the patient-related, primary tumorrelated, and SLN-related characteristics used as potential predictive factors for nonsentinel axillary node metastases. Multivariate analysis identified the size of the primary tumor (P = .046) and the size of its SLN metastasis (P = .008) as significant predictors of nonsentinel axillary node involvement.
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| DISCUSSION |
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Earlier reports on neoadjuvant therapy for patients with large breast tumors often used clinical rather than histological staging before neoadjuvant chemotherapy.17,18 Inaccurate estimation of the size of the primary tumor and the status of regional axillary lymph nodes may have concealed any survival benefit of neoadjuvant therapy. More recent investigators have therefore recommended pathologic staging of the axilla before neoadjuvant chemotherapy.6
The role of axillary ultrasound and FNA biopsy to identify axillary metastases is intriguing and may serve as a potential alternative to surgical staging of the axilla. In a study of 147 patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy, Kuerer et al.19 reported that the sensitivity of axillary sonography in identifying axillary metastases was significantly higher than that of physical examination (P = .012) when performed before induction chemotherapy. Among the 55 patients in whom the findings of both physical and ultrasound examination of the axilla were negative after induction chemotherapy, 29 patients (53%) were found to have axillary lymph node metastases on pathologic examination of the axillary contents. Unfortunately, the presence of axillary metastases was not confirmed cytologically by FNA after induction chemotherapy. Because neoadjuvant chemotherapy has been reported to completely clear axillary lymph node metastases in approximately 23% of patients with locally advanced breast cancer in one series,20 histopathologic assessment of the axilla after induction therapy may be valuable. Ultrasound-guided FNA biopsy of suspicious nodes or SLND in this setting may eliminate the need for ALND in select patients.
Because SLND is highly accurate and minimally invasive, it may offer an advantage over ALND. The feasibility of SLND in patients with large tumors has recently been demonstrated.6,14 In our study, an SLN was identified in all 41 patients. Subsequent SLND and completion ALND revealed axillary lymph node metastases in 31 patients, 30 of whom had tumor-positive SLNs. Thus SLND produced only one false-negative result. This patient, with a history of prior axillary surgery, insisted on SLND, despite extensive counseling against the procedure. Four years previously, she had undergone lumpectomy, SLND, and postoperative breast irradiation for a T1 tumor of the ipsilateral breast, and it is quite likely that the locoregional lymphatic drainage pattern was altered by prior breast and axillary surgery and irradiation. In cases such as this, ALND with or without SLND should be performed, as was done. Even with the inclusion of this case, our SLN identification rate, accuracy rate, and false-negative rate were in accordance with those reported in other series6,810,14 (Table 3). Moreover, ours was the only study in which all resected tumor specimens had a diameter
5 cm.
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Published literature contains two other studies of SLND for large primary tumors, both of which focused on T2 tumors (
2 cm but
5 cm).6,14 In the study of Cohen et al.,14 SLND was undertaken after neoadjuvant therapy. SLNs were identified in 82% of cases and accurately predicted regional nodal status in 90%. The false-negative rate was 10%. In our study, two patients received neoadjuvant therapy; subsequent SLND accurately reflected axillary nodal status in both cases. One patient had one tumor-positive SLN and three tumor-positive nonsentinel nodes. Another patient had no evidence of sentinel or nonsentinel metastases. However, the role of SLND after neoadjuvant chemotherapy needs to be better defined and validated in a larger trial. It is unclear whether induction chemotherapy disrupts or alters locoregional lymphatics. Therefore, we do not perform SLND after neoadjuvant chemotherapy outside of a protocol. Our current indication for administering neoadjuvant therapy is to facilitate breast-conservation surgery, because multiple studies have shown that neoadjuvant therapy does not improve survival.24 If a patient desires a mastectomy, or a breast conservation is thought to be possible with acceptable cosmesis, then we would proceed with definitive surgery without neoadjuvant chemotherapy.
Because breast-conserving surgical management of a large tumor is usually preceded by neoadjuvant therapy, regardless of the status of the regional axillary nodes, SLND may be used to determine the need for ALND in these patients. Although the incidence of axillary metastasis is low for patients with small tumors,15 it increases progressively with size of the primary tumor, approaching 80% for T3 tumors.6 In our study of patients with tumors
5 cm, the rate of axillary metastasis was 76%. If the axilla is not treated with either ALND or radiotherapy, approximately half (38% in our series) of node-positive patients may develop same-basin recurrence within 5 years.21,22 Therefore, SLND should be performed in patients with large tumors to identify those patients at risk for axillary relapse. Because axillary failure rates are reportedly higher after axillary radiotherapy than ALND (2%19% vs. 1%),23 we favor ALND for regional control. Indeed, no patient in our study had developed axillary relapse at a median follow-up of 36 months. We also favor completion ALND for patients with tumor-positive SLNs because more accurate prognostic information can be obtained when the status of the entire nodal basin is known.24
Although the rate of axillary metastases in our study is high, closer examination of our data indicates that SLND alone may offer adequate regional control in certain patients with large primary breast tumors. Of the 41 patients in our study, 10 had tumor-free axillary nodes and 10 had axillary metastases confined to SLNs. The latter 10 included all 3 patients whose SLN involvement was strictly micrometastatic (tumor focus
2 mm in diameter). In the recent report of Bedrosian et al.,6 the size of an SLN metastasis (macro- vs. micro-) correlated significantly with nonsentinel axillary metastasis from a large primary breast tumor. Nonsentinel involvement was identified in 3 of 8 patients with SLN micrometastasis versus 21 of 22 patients with SLN macrometastasis (P = .002). Likewise, we demonstrated a correlation between size of SLN metastasis and presence of nonsentinel axillary metastasis in patients with smaller tumors.25 Five of 69 (7%) patients with SLN micrometastasis and 49 of 89 (55%) patients with SLN macrometastasis had nonsentinel axillary metastasis (P < .0001). Among the patients with SLN micrometastasis, 0 of 33 (0%) with IHC-discovered micrometastasis and 5 of 36 (14%) with H&E-discovered micrometastasis had nonsentinel axillary metastasis (P = .021). It is possible that this subset of patients with SLN micrometastasis may represent the best candidates for axillary radiotherapy rather than ALND.
In our study we used logistic regression analysis of various patient-related, primary tumor-related, and SLN-related characteristics to identify potential predictors of nonsentinel axillary metastasis (Table 2) and thereby determine which patients should undergo ALND after SLND. By multivariate analysis, the only two predictors of nonsentinel metastasis were primary tumor size
7 cm and SLN macrometastasis (P = .045 and P = .008, respectively). Although SLN micrometastasis did not predict a low likelihood of additional axillary metastases, the lack of statistical significance may be attributed to our small sample size. If we assume that SLND is sufficient for regional control when nodal tumor is absent or confined to a micrometastatic focus in an SLN, then 13 patients (32%) in our study need not have undergone ALND. This is not an insignificant number when applied nationally.
In conclusion, we have shown that SLND is possible in patients with large breast tumors and clinically negative axillae. The rates of SLN identification, accuracy, and false negatives compare favorably with those reported for studies of SLND in patients with smaller breast tumors.810 In patients with large breast tumors, focused pathologic examination of the SLN could identify the best candidates for ALND. Development of a reliable and accurate means of detecting nonsentinel axillary metastasis might further decrease the number of patients requiring ALND.
| Acknowledgments |
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| Footnotes |
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Received for publication March 16, 2001. Accepted for publication June 20, 2001.
| REFERENCES |
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