FROM SABCS 2023
Axillary lymph node dissection may be unnecessary if breast cancer patients with one or two positive sentinel lymph nodes plan to have adjuvant nodal radiation, according to a major Scandinavian trial presented at the San Antonio Breast Cancer Symposium.
"It means that you don't need to dissect the axilla if you" are going to "radiate the axilla." "For the US, that's the conclusion because there are still centers that do both, and that's out," lead investigator Jana de Boniface, MD, PhD, a breast cancer surgeon at the Karolinska Institutet, Stockholm, said in an interview.
The study added to a persistent theme at this year's meeting, protecting breast cancer patients from doing too much and causing unnecessary harm. Some even wondered if 5 years of endocrine therapy is necessary.
Dr Boniface shared her thoughts after presenting the Scandinavian trial, SENOMAC, which she led.
SENOMAC randomized 1204 patients with one or two positive sentinel lymph nodes to axillary dissection; 1335 with the same finding were randomized to no dissection.
Subjects had clinically T1-3 N0 primary breast cancer. About 89% in both arms went on to adjuvant radiation, including nodal radiation, and almost all also went on to systemic therapy, which included endocrine therapy in over 90%. Only about 2% of subjects had neoadjuvant therapy.
At a median follow-up of nearly 4 years, recurrence-free survival was virtually identical in both groups, with 8% of patients in the dissection arm and 7.1% in the no-dissection group having recurrences. Estimated 5-year recurrence-free survival was just shy of 90% in both groups. Skipping dissection was strongly non-inferior to having one (P < .001).
SENOMAC "clearly shows that you don't need to dissect the axilla if you have one to two positive sentinel lymph nodes" so long as patients have adjuvant nodal radiation. Recurrence-free survival "curves practically overlap, and we cannot see any difference between the two groups," Dr Boniface said.
Meanwhile, the dissection group fared worse on patient reported outcomes. Overall survival outcomes, the primary endpoint of the trial, are expected within 2 years.
The goal of the trial, the largest to date to look into the issue, was to fill gaps in the literature. Similar outcomes were reported around a decade ago in patients with low sentinel lymph node burdens, but the extensive exclusion criteria raised questions about general applicability.
In contrast, SENOMAC was widely inclusive. Over a third of patients had mastectomies, over a third had sentinel lymph node extracapsular extension, almost 6% had T3 disease, almost 20% had lobular carcinoma, 40% were 65 years or older, and tumors were as large as 15.5 cm.
The findings held regardless of those and other factors on subgroup analyses, including estrogen receptor and HER2 status and the number of additional positive nodes retrieved in the dissection group.
Andrea V. Barrio, MD, the study discussant and a breast cancer surgeon at Memorial Sloan Kettering Cancer Center, New York, agreed with the message from SENOMAC.
"Based on this, ALND [axillary lymph node dissection] should not be considered standard in patients with clinical T1-3 N0 breast cancer with one to two positive sentinel nodes, with or without microscopic extracapsular extension, undergoing lumpectomy or mastectomy," provided nodal adjuvant radiotherapy is indicated, she said.
Although adjuvant nodal radiation for patients with one to three positive sentinel nodes is standard of care in Denmark and Sweden, where most of the patients in SENOMAC were located, practices vary widely in the United States. If adjuvant radiation isn't used, "then ALND [is still] indicated," Dr Barrio said, but in either case, "only one is needed."
In keeping with the de-escalation theme at the 2023 symposium, both Dr Boniface and Dr Barrio noted that trials are now underway to find patients who can avoid any axillary treatment at all if they have just one or two positive sentinel lymph nodes.
Preoperative axillary ultrasound was mandatory in SENOMAC and patients with nonpalpable suspicious axillary lymph nodes were enrolled.
Thirty six were positive on fine-needle aspiration and randomized into the study, but when asked, Dr Boniface didn't have the data immediately at hand on how they fared.
The work was funded by the Swedish Research Council, Nordic Cancer Union, and others. Dr Boniface and Dr Barrio didn't have any disclosures.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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