Sentinel Lymph Node Staging: Not Only for N0
Boughey JC, Suman VJ, Mittendorf EA, et al
JAMA. 2013;310:1455-1461
Sentinel lymph node (SLN) biopsy provides reliable nodal staging information with less morbidity than axillary lymph node dissection (ALND) for patients with clinically node-negative breast cancer. The application of this technique for patients who initially had clinically node-positive disease and received neoadjuvant chemotherapy is unclear. A high false-negative rate has been reported in prior studies. The American College of Surgeons Oncology Group (ACOSOG) designed a multicenter, prospective study to determine the false-negative rate for SLN biopsy following chemotherapy for women with biopsy-proven node-positive breast cancer.
The ACOSOG investigators conducted a prospective, multicenter trial from July 2009 to June 2011. Following chemotherapy, patients underwent SLN biopsy followed by ALND. The primary endpoint was to determine the false-negative rate of SLN biopsy. Investigators used 10% as the limit of acceptability for the procedure, because this is the expected rate for women with clinically negative axillae undergoing SLN biopsy prior to systemic therapy.
A total of 756 women were enrolled in the study. Of 663 evaluable patients with cN1 disease (disease in movable axillary lymph nodes), 649 underwent chemotherapy followed by both SLN biopsy and ALND. In 46 patients (7.1%) an SLN could not be identified. In 78 patients (12%) excision was limited to 1 SLN. Of the remaining 525 patients who underwent excision of 2 or more SLNs, no cancer was identified in the axillary lymph nodes of 215 patients, yielding a pathologic complete nodal response of 41.0%. In 39 patients, cancer was not identified in the SLNs but was found in lymph nodes, resulting in a false-negative rate of 12.6%.
For the entire group of women who presented with biopsy-proven node-positive disease and underwent neoadjuvant chemotherapy, the usefulness of SLN biopsy after chemotherapy could not be proven because the false-negative rate exceeded predefined parameters set by the investigators. However, the authors identified certain important factors that influenced the likelihood of a false-negative SLN biopsy, including use of a dual-agent mapping technique, retrieval of 3 or more SLNs, and careful pathologic analysis with multilevel cuts in specimen processing.
The study by Boughey and colleagues showed that with dual-agent mapping and recovery of 2 or more SLNs, the rate of false-negative SLN biopsies following neoadjuvant chemotherapy fell into a range generally considered to be acceptable for this procedure. Kruehn and colleagues found a clear relationship between the number of SLNs found with SLN biopsy and false-negative rates following neoadjuvant chemotherapy in the SENTINA trial. With removal of 1 SLN, the false-negative rate in the SENTINA trial was 31%, for 2 it was 21%, and for 3 or more it fell below the investigators' threshold of 10%. Taken together, these studies show us that considering SNL biopsy in the setting of a favorable response to neoadjuvant therapy is a reasonable option in the hands of an experienced surgeon.
Abstract
Sentinel Lymph Node Surgery After Neoadjuvant Chemotherapy in Patients With Node-Positive Breast Cancer
Boughey JC, Suman VJ, Mittendorf EA, et al
JAMA. 2013;310:1455-1461
Study Summary
Sentinel lymph node (SLN) biopsy provides reliable nodal staging information with less morbidity than axillary lymph node dissection (ALND) for patients with clinically node-negative breast cancer. The application of this technique for patients who initially had clinically node-positive disease and received neoadjuvant chemotherapy is unclear. A high false-negative rate has been reported in prior studies. The American College of Surgeons Oncology Group (ACOSOG) designed a multicenter, prospective study to determine the false-negative rate for SLN biopsy following chemotherapy for women with biopsy-proven node-positive breast cancer.
The ACOSOG investigators conducted a prospective, multicenter trial from July 2009 to June 2011. Following chemotherapy, patients underwent SLN biopsy followed by ALND. The primary endpoint was to determine the false-negative rate of SLN biopsy. Investigators used 10% as the limit of acceptability for the procedure, because this is the expected rate for women with clinically negative axillae undergoing SLN biopsy prior to systemic therapy.
A total of 756 women were enrolled in the study. Of 663 evaluable patients with cN1 disease (disease in movable axillary lymph nodes), 649 underwent chemotherapy followed by both SLN biopsy and ALND. In 46 patients (7.1%) an SLN could not be identified. In 78 patients (12%) excision was limited to 1 SLN. Of the remaining 525 patients who underwent excision of 2 or more SLNs, no cancer was identified in the axillary lymph nodes of 215 patients, yielding a pathologic complete nodal response of 41.0%. In 39 patients, cancer was not identified in the SLNs but was found in lymph nodes, resulting in a false-negative rate of 12.6%.
For the entire group of women who presented with biopsy-proven node-positive disease and underwent neoadjuvant chemotherapy, the usefulness of SLN biopsy after chemotherapy could not be proven because the false-negative rate exceeded predefined parameters set by the investigators. However, the authors identified certain important factors that influenced the likelihood of a false-negative SLN biopsy, including use of a dual-agent mapping technique, retrieval of 3 or more SLNs, and careful pathologic analysis with multilevel cuts in specimen processing.
Commentary
The study by Boughey and colleagues showed that with dual-agent mapping and recovery of 2 or more SLNs, the rate of false-negative SLN biopsies following neoadjuvant chemotherapy fell into a range generally considered to be acceptable for this procedure. Kruehn and colleagues found a clear relationship between the number of SLNs found with SLN biopsy and false-negative rates following neoadjuvant chemotherapy in the SENTINA trial. With removal of 1 SLN, the false-negative rate in the SENTINA trial was 31%, for 2 it was 21%, and for 3 or more it fell below the investigators' threshold of 10%. Taken together, these studies show us that considering SNL biopsy in the setting of a favorable response to neoadjuvant therapy is a reasonable option in the hands of an experienced surgeon.
Abstract
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