Sentinel lymph node biopsy (SLNB) is the standard of care for axillary node staging in early breast cancer, but previous studies have shown that removal of axillary lymph nodes has no therapeutic effect.
The finding raises a question: Is SLNB even necessary when preoperative axillary imaging is negative?
A new randomized trial addresses the question and brings much “welcome clarity” to the issue, Seema Khan, MD, a surgical oncologist and breast cancer researcher at Northwestern University, Chicago, said in an editorial to the trial, both of which were published in JAMA Oncology.
In short, European
At a median of follow-up of 5.7 years, distant disease-free survival and other outcomes were essentially equivalent between 708 women randomized to SLNB followed by full axillary dissection if nodes are positive and 697 other women randomized to observation without SLNB.
Adjuvant therapies were not significantly different between the two groups largely because adjuvant decisions were driven by tumor characteristics, not axillary studies.
The results support “the argument that sentinel node positivity is not, in and of itself, a critical parameter that determines therapeutic plans and outcomes in patients with stage I breast cancer. This is a major accomplishment of the SOUND [Sentinel Node vs. Observation After Axillary Ultra-Sound] trial, which will be strengthened when longer-term data become available” at 10-year follow up, Dr. Khan said.
Investigators led by Oreste Davide Gentilini, MD, a breast cancer surgeon at San Raffaele Scientific and Research Hospital, Milan, estimated that, of the 2.3 million breast cancers diagnosed globally each year, the study suggests “that approximately 500,000 patients might be able to take advantage of the total omission of axillary surgery,” sparing women lymphedema and other serious side effects and saving health care systems substantial dollars.
A case-by-case decision
The study included women of all ages, with a median age of 60 years.
Subjects had a single tumor 0.8-1.5 cm across with negative preoperative axillary ultrasonography. Almost 90% had estrogen receptor ERBB2 (formerly HER2) positive tumors. Almost all of the subjects had radiotherapy, and about 20% of women in each arm also had chemotherapy.
The trial was conducted in 18 sites, most in Italy with other sites in Switzerland, Spain, and Chile.
Overall, 13.7% of women in the SLNB group turned out to have positive axillary nodes, with 0.6% having four or more positive nodes.
However, it didn’t seem to make a difference in the overall study results.
Five-year distant disease-free survival was 97.7% in the SLNB group and 98% in the observation arm (P for noninferiority = .02).
Secondary outcomes were also essentially identical, including local/regional relapse (1.7% with SLNB versus 1.6% without); distant metastases (1.8% vs. 2%), and death from breast cancer (1% vs. 0.6%). The cumulative incidence of axillary lymph node recurrences in the observation arm was just 0.4%.
“These findings suggest that patients with BC of a diameter equal to or smaller than 2 cm and a negative result on preoperative axillary lymph node ultrasonography can be safely spared any axillary surgery whenever the lack of pathological information does not affect the postoperative treatment plan,” Dr. Gentilini and associates concluded.
The team cautioned that decision to forgo SLNB must be made on a case-by-case basis in a multidisciplinary setting because there are still situations where nodal pathology is relevant, for instance when deciding to add chemotherapy to endocrine treatments in premenopausal women with endocrine-responsive disease.
Only about 20% of the subjects were under 50 years old and the team didn’t break down their results by age, which makes it difficult to apply their results to the situation.
The work was funded by the European Institute of Oncology. Dr. Khan didn’t have any disclosures. Dr. Gentilini reported personal fees from AstraZeneca, Bayer, BD, Eli Lilly, and MSD. Two other investigators also reported personal fees from those and/or other companies.