Sentinel Node Surgery Correctly Stages Lymph Nodes Following Neoadjuvant Chemotherapy
Axillary lymph node dissection (ALND) may not be necessary after neoadjuvant chemotherapy in most patients, according to investigators who found that sentinel lymph node (SLN) dissection correctly staged more than 90% of patients.
A study of the American College of Surgeons Oncology Group, ACOSOG Z1071, evaluated whether SLN surgery may sufficiently substitute for ALND as a less invasive procedure.
“We showed that sentinel lymph node surgery correctly identified the nodal status in 91.2% of patients who were node-positive at presentation and who underwent neoadjuvant chemotherapy,” said Judy C. Boughey, MD, Associate Professor of Surgery, Department of Surgery, Mayo Clinic in Rochester, MN.
A number of factors helped to reduce the chance of false-negative results with SLN surgery. Dr Boughey said she would “feel safe incorporating sentinel node surgery in clinical practice in cases where patients have a good clinical response to chemotherapy, undergo sentinel node mapping with standardization of the technique, and have 3 or more sentinel nodes identified. I feel the false-negative rate is acceptable in that group.”
SLN dissection is routinely used for patients initially diagnosed with node- negative disease. The study evaluated whether SLN dissection could be safely used in patients with node-positive breast cancer, who at this time typically undergo ALND instead.
“The question is whether removal of the lymph nodes with an axillary dissection is needed, or whether less invasive surgery would reliably identify patients who still have disease in the lymph nodes and which patients have negative nodes,” Dr Boughey pointed out. “Our hypothesis was that sentinel node surgery is an accurate method of axillary staging in these patients.”
The goal was to have a false-negative detection rate of ?10%, she noted.
Patients Underwent Both Procedures
The study included 756 patients with node-positive breast cancer who received neoadjuvant chemotherapy, of whom 637 underwent both SLN dissection and ALND.
SLN surgery correctly identified the nodal status in 91.2% of the patients, including 40% who were ultimately node negative and 60% with residual nodal disease. Of the 382 patients with residual disease, ALND confirmed that 326 were indeed sentinel node positive, whereas 56 patients were sentinel node negative but node positive according to the axillary dissection. Sentinel node surgery, therefore, correctly identified the nodal status in 91.2% of the patients in this study, Dr Boughey reported.
False-Negative Rates Lower in Some Groups
The rate of false negatives among patients with at least 2 sentinel nodes examined was 12.6%, which is higher than their stated goal. They then looked at factors that might have affected this rate, and they found some differences.
The rate was lower (10.8%) when both blue dye and radiolabeled colloid were used and when at least 3 sentinel nodes were examined. Of the 78 patients with clinical N1 disease who had only 1 sentinel node examined, the false-negative rate climbed to 31.5%.
When histologic changes were present, the false-negative rate was 10.8%; when histology was unknown, the rate was 13.5%. Dr Boughey therefore emphasized that knowledge of the tumor’s histology could boost the accuracy of the procedure. When a clip was placed in the lymph nodes at diagnosis, the false-negative rate dropped to 7.4%. There was no significant difference according to clinical tumor stage.
“Sentinel lymph node surgery is a useful tool for the detection of residual nodal disease in women with node-positive disease receiving neoadjuvant chemotherapy, but surgical technique is important for minimizing the false-negative rate,” Dr Boughey advised.