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Sentinel lymph node surgery may detect residual disease in node-positive breast cancer
SAN ANTONIO — Use of sentinel lymph node surgery among patients with node-positive breast cancer who had been treated with neoadjuvant chemotherapy may reduce the extent of axillary surgery, according to study results.
Judy C. Boughey, MD, associate professor of surgery at the Mayo Clinic in Rochester, Minn., presented the findings at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium.
The utility of sentinel lymph node surgery after chemotherapy in patients presenting with node-positive breast cancer has not been clearly determined, Boughey said. The American College of Surgeons Oncology Group (ACOSOG) Z1071 trial was designed to evaluate this surgery after chemotherapy in women presenting with node positive disease.
“We were looking to minimize axillary lymph node dissection (ALND) in this group,” Boughey said.
Eligible participants had clinical T0-4, N1-2, M0 breast cancer and were treated with neoadjuvant chemotherapy. All patients were to undergo sentinel lymph node surgery followed by ALND.
The primary outcome measure was false negative rate in women with cN1 disease with two or more sentinel lymph node surgeries reviewed. Metastases >.2 mm on H & E comprised positive sentinel lymph nodes.
The initial enrollment included 756 patients from 136 institutions. Enrollment occurred from July 2009 to July 2011.
A sentinel lymph node was identified in 92.7% of 689 patients. That rate was 92.9% among 651 patients with cN1 disease and 89.5% among 39 patients with cN2 disease.
Sentinel lymph node correctly identified nodal status in 91.2%.
There were 310 patients with residual nodal disease and 39 patients with negative sentinel lymph nodes.
“The false negative rate was 12.6%,” Boughey said.
Researchers observed a 10.8% false negative rate among patients who underwent dual tracer technique, which Boughey defined as blue dye and radiolabelled colloid.
“The false negative also decreased as the number of sentinel lymph nodes examined increased,” Boughey said.
A clip was placed at lymph node diagnosis in 32.8% of patients. The false negative rate was 7.4% in this cohort of patients.
There were no false negatives reported among patients with cN2 disease. The false negative rate was 12% among patients with cN1 and cN2 disease with more than two sentinel lymph nodes resected, and 10.3% among those with cN1 and cN2 disease with dual tracer used.
A complete pathologic response was observed in 40.3% of patients. The sentinel lymph node was the only site of disease in 37% of patients with a positive result in that site.
“Sentinel lymph node surgery is a useful tool for detection of residual nodal disease in women with node positive disease receiving neoadjuvant chemotherapy,” Boughey said. “Surgical technique is important to minimize false negatives.”
Use of dual tracer and resection of a minimum of two sentinel lymph nodes is important to minimize false negatives, Boughey said. Clip placement at diagnosis may improve the accuracy of sentinel lymph node procedures, she added.
“Use of this surgery in these patients will enable reduction of invasiveness of axillary surgery,” Boughey said.
Kelly K. Hunt, MD, FACS, professor of surgery at The University of Texas MD Anderson Cancer Center and senior author of the study, added: “SLN surgery after chemotherapy is technically more challenging than SLN in patients presenting for surgery before chemotherapy. Therefore, using a more standardized approach will make this more applicable in the surgical management of our breast cancer patients.”
For more information:
Boughey J. #S2-1. Presented at: the 2012 CTRC-AACR San Antonio Breast Cancer Symposium; Dec. 4-8, 2012; San Antonio.
Disclosure: Boughey reports no relevant financial disclosures.
Perspective
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Sentinel node biopsy (SN) after neoadjuvant chemotherapy is accepted in clinically node-negative women but controversial in those with nodal involvement at presentation. ACOSOG Z1071 provides important data on its accuracy in a cohort with biopsy-proven nodal disease. The false-negative rate of 12.6% with removal of two or more nodes is acceptable when one considers that therapeutic decisions are usually made on the basis of nodal stage at presentation , and the risk of axillary first failure in the multimodality therapy setting is less than one-third of the false-negative rate.
The false-negative rate declined to 9% with removal of three nodes, emphasizing that attention to technique and removal of all SNs is important. The more interesting question is what to do with the patient who has only a single SN identified. The false-negative rate in this group was 31%. Does the anatomical fact of only a single SN really necessitate axillary dissection? Does the removal of a few non- SNs that are negative resolve this issue? Information on the number of positive nodes present in patients with false negative SNs will be important in addressing this question. Overall, this study represents another important step in tailoring the extent of surgery to the extent of disease to reduce morbidity of treatment.
Perspective
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This study is important, as it provides new insight into the management of the axilla in patients who present with axillary metastasis of breast cancer and who are treated with chemotherapy before surgery. It is very encouraging that 40% of patients had disease eradicated in the lymph nodes by the use of chemotherapy prior to surgery. The study also suggests that, in the future, we may be able to further reduce the amount of axillary surgery and the associated complications of surgery in this subset of breast cancer patients who present with more advanced disease. This study sets the stage for further studies to personalize the surgical care of axilla breast cancer patients, which can ultimately lead to fewer interventions without compromising oncologic outcomes.
