SAN ANTONIO — Axillary lymph node dissection is the current standard of care in breast cancer when metastases are found in sentinel lymph nodes after neoadjuvant chemotherapy.
However, what to do when isolated tumor cells instead of outright metastases are found in sentinel nodes is an open question. Some surgeons opt for a full axillary dissection while others do not, and there is no standard of care, explained Giacomo Montagna, MD, a breast cancer surgeon at Memorial Sloan Kettering Cancer Center, New York City.
The study led and presented by Dr. Montagna at the San Antonio Breast Cancer Symposium brings some much-needed clarity to the issue.
The findings argue strongly against “routine axillary lymph node dissection” — with its considerable morbidities — “in patients with residual isolated tumor cells after neoadjuvant chemotherapy,” Dr. Montagna said.
Study discussant Elizabeth Mittendorf, MD, PhD, a breast cancer surgeon at Brigham and Women’s Hospital, Boston, agreed.
“It appears that the presence of isolated tumor cells in the sentinel nodes does not negatively impact oncologic outcomes. These additional data allow us to debunk some of the surgical dogma we grew up with, specifically that lymph node dissection is required for either survival or local control,” Dr. Mittendorf said.
However, there was concern among audience members that the information gleaned from a full dissection might still be needed to guide follow-on adjuvant therapy decisions.
Dr. Mittendorf didn’t think so. Although additional positive lymph nodes were found in almost a third of women who had axillary dissections in the review, the majority of involved nodes simply had more isolated tumor cells; macrometastases were found in just 5% of cases.
So, for most patients, additional information from axillary dissections is “unlikely needed to inform adjuvant therapy, and in fact,” based on the 5% figure, “we are thinking we would have to do well over a hundred lymph node dissections in such patients to inform treatment recommendations for fewer than five. This comes at the cost of fair morbidity,” she said.
Study details
The retrospective study, dubbed OPBC05/EUBREAST-14R/ICARO, included 583 women with cT1-4 N0-3 breast cancer treated at 62 centers in 18 countries. The majority of subjects were from the United States and Europe.
Every patient was found to have isolated tumor cells (ITCs) in their sentinel lymph nodes after neoadjuvant chemotherapy (NAC), which generally included anthracycline and taxane-based regimens. The majority of patients did not have a pathologic complete response to NAC.
Overall, 182 patients (31%) had a subsequent axillary lymph node dissection; the rest did not.
Dissections were more common in the presence of lymphovascular invasion and N2/N3 disease as well as when fewer lymph nodes were removed and when ITCs were found during surgery on frozen section, which was the case in a quarter of patients.
Additional positive nodes were found in 30% of patients in the dissection group and consisted of more nodes with ITCs in 18%, micrometastases in 7%, and macrometastases in 5%. Receptor status and nodal status at presentation did not have an impact on the likelihood of finding macrometastases.
The main finding of the study was that there were no statistically significant differences in recurrence outcomes between the two groups.
The 5-year rate of isolated axillary recurrence was 1.7% with axillary lymph node dissection (ALND) versus 1.1% without it. The 5-year rate of any invasive recurrence was 16% in the ALND arm and 19% in the no-dissection group.
The median age in the study was 48 years. The majority of patients (57%) had clinical T2 tumors. Most were HR positive and either HER2 negative (41%) or HER2 positive (28%).
Regional nodal radiation was more common in the ALND group, 82% versus 75%. The dissection arm had a mean of 2.8 sentinel lymph nodes removed versus 3.5 in the no-dissection group.
“The likelihood of finding additional positive lymph nodes in patients with residual ITCs after NAC is lower than in patients with residual micro- and macrometastases. In the majority of cases, they contain ITCs. Nodal recurrence after omission of ALND is rare in this population,” the investigators concluded in their abstract.
The work was funded by EUBREAST. Dr. Montagna doesn’t have any disclosures. Dr. Mittendorf has several industry ties, including being an advisor for Roche, AstraZeneca, and Moderna and a speaker for Merck.