Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy in Patients With Node-Positive Breast Cancer

The results of ACOSOG Z1071 clinical trial

Among women with clinically node-positive (cN1) breast cancer receiving neoadjuvant chemotherapy, who had 2 or more sentinel lymph nodes (SLNs) examined, the false-negative rate (FNR) did not meet the predefined criteria in the ACOSOG Z1071 study. The authors speculate that when 2 or more SLNs are identified by a combination of radiotracer and dye mapping in patients who become clinically node-negative after chemotherapy, there may still be a role for staging with SLN biopsy. They wrote that the changes in approach and patient selection that result in greater sensitivity would be necessary to support the use of SLN as an alternative to axillary lymph node dissection (ALND). The results are reported in the 9 October 2013 issue of JAMA. Their report is accompanied by an editorial article that characterizes the appropriateness of SLN surgery in that setting uncertain.

Axillary lymph node dissection reliably identifies lymph node metastases and results in in a high rate of local cancer control, even in patients who initially present with node-positive disease. In patients initially presenting with node-negative breast cancer, ALND has been replaced by SLN biopsy, which is much less morbid procedure. Sentinel lymph node provides reliable nodal staging information for patients with clinically node-negative (cN0) breast cancer. The application of SLN for staging the axilla following chemotherapy for women who initially had node-positive cN1 breast cancer is unclear because of high false-negative results reported in previous studies.

Dr Judy Boughey of the Department of Surgery, Mayo Clinic, Rochester, Minnesota, USA and colleagues present the results of a prospective, multicentre trial with the primary aim of determining the FNR of SLN in patients with clinically node-positive disease receiving neoadjuvant chemotherapy.

The American College of Surgeons Oncology Group (ACOSOG) Z1071 trial enrolled women from 136 institutions from July 2009 to June 2011 who had clinical T0 through T4, N1 through N2, M0 breast cancer and received neoadjuvant chemotherapy. Following chemotherapy, patients underwent both SLN surgery and ALND. The primary end point was the FNR of SLN surgery after chemotherapy in women who presented with clinically node-positive disease. The investigators evaluated the likelihood that the FNR in patients with 2 or more SLNs examined was greater than 10%, the rate expected for women undergoing SLN surgery who present with clinically node-negative disease.

In total, 756 women were enrolled in the study. Of 663 evaluable patients with cN1 disease, 649 underwent chemotherapy followed by both SLN surgery and ALND. A SLN could not be identified in 46 patients (7.1%). Only 1 SLN was excised in 78 patients (12.0%). Of the remaining 525 patients with 2 or more SLNs removed, no cancer was identified in the axillary lymph nodes of 215 patients, yielding a pathological complete nodal response of 41.0%. In 39 patients, cancer was not identified in the SLNs but was found in lymph nodes obtained with ALND, resulting in an FNR of 12.6%.

The authors concluded that among women with clinically node-positive breast cancer receiving neoadjuvant chemotherapy who had 2 or more SLNs examined, the FNR was not found to be 10% or less.

Trial Registration clinicaltrials.gov Identifier: NCT00881361.

References

J. Boughey, V. Suman, E. Mittendorf, et al. Sentinel Lymph Node Surgery After Neoadjuvant Chemotherapy in Patients With Node-Positive Breast Cancer. The ACOSOG Z1071 (Alliance) Clinical Trial. JAMA. 2013;310(14):1455-1461. doi:10.1001/jama.2013.278932.

M. Morrow and C. Dang.  Sentinel Node Biopsy After Neoadjuvant ChemotherapyA New Standard for Patients With Axillary Metastases? JAMA. 2013;310(14):1449-1450. doi:10.1001/jama.2013.7844.