SLNB after neoadjuvant breast cancer therapy not yet viable management strategy

Improved patient selection and changes in approach that lead to greater sensitivity are necessary to support the use of sentinel lymph node biopsy as an alternative to axillary lymph node dissection in women who underwent neoadjuvant chemotherapy for breast cancer, according to study results.

Sentinel lymph node biopsy (SLNB) provides reliable nodal staging information with less morbidity than axillary lymph node dissection in patients with node-negative breast cancer. However, the staging of the axilla following chemotherapy in patients with initial node-positive and clinically node-negative breast cancer is not known, according to background information provided by researchers.

The current study included 649 women with disease in movable axillary lymph nodes (cN1 disease) who had undergone chemotherapy. The women, who had various stages of breast cancer, were enrolled on the American College of Surgeons Oncology Group Z1071 trial, conducted at 136 institutions between July 2009 and June 2011.

After chemotherapy, the women underwent sentinel lymph node surgery and axillary lymph node dissection. Researchers evaluated whether the false-negative rate in women with two or more sentinel lymph nodes would exceed 10%, the rate expected for women with clinically node-negative breast cancer.

A sentinel lymph node could not be identified in 46 patients (7.1%). Seventy-eight patients (12%) had one sentinel lymph node excised.

Two or more sentinel lymph nodes were excised from the remaining 525 patients. No cancer was detected in 215 of those patients, translating to a 41% (95% CI, 36.7-45.3) pathologic complete nodal response rate.

Axillary lymph node dissection identified cancer in 39 patients who did not have cancer identified in the sentinel lymph nodes, equating to a false-negative rate of 12.6%.

“There is an increasing menu of targeted therapies available for breast cancer,” researchers wrote. “As physicians move away from the ‘one size fits all’ approach, the prognostic information obtained from residual nodal disease after neoadjuvant therapy is likely to become increasingly important in determining the need for additional therapy. If that is true, research in ways to improve the performance of sentinel lymph node biopsy after neoadjuvant therapy is needed for this approach to become a viable management strategy.”

Chau T. Dang

In an accompanying editorial, Monica Morrow, MD, and Chau T. Dang, MD, both of Memorial Sloan-Kettering Cancer Center, wrote: “Decisions about using systemic therapy after neoadjuvant therapy are not dependent upon identifying residual cancer in lymph nodes when all the planned chemotherapy is given preoperatively to maximize the cancer response. However, accurate detection of residual lymph node cancer may be important in prospective trials of novel agents in which post-neoadjuvant treatment decisions, including possible research protocol participation, may hinge on the detection of residual disease.”

It also is important to remember patients with residual cancer after neoadjuvant therapy have at some level of resistance to systemic therapy, Morrow and Dang wrote.

“These patients might require more aggressive local therapy such as complete axillary lymph node dissection or radiation therapy to the axilla,” they wrote. “Because there is no information regarding long-term local cancer control or survival for patients initially presenting with clinically node-positive disease who receive neoadjuvant therapy but have a 20% to 30% rate of residual cancer in the axilla following sentinel lymph node biopsy, we do not believe that SLNB, regardless of the number of sentinel lymph nodes removed, can be considered standard management for these patients.”

For more information:

Boughey JC. JAMA. 2013;doi:10.l001/jama.2013.7844.
Morrow M. JAMA. 2013;doi:10.l001/jama.2013.7844.

Disclosure: The researchers report grant funding from Genentech.