SAN ANTONIO – Sentinel lymph node detection after neoadjuvant chemotherapy (NAC) is a safe and feasible strategy for preventing unnecessary systematic lymphadenectomy in patients with operable breast cancer and no clinical signs of cancer in the axillary lymph nodes prior to NAC, according to findings from the French prospective multicenter GANEA 2 trial.
However, further study is needed to assess the clinical impact of the 12% false negative rate associated with sentinel lymph node detection (SLND) in the current study, according to Jean-Marc Classe, MD, who reported the findings at the San Antonio Breast Cancer Symposium.
SLND was feasible in that it was achieved in 570 of 590 women (97%) with large operable breast tumors and negative findings on axillary sonography with fine needle cytology who were enrolled in the study, said Dr. Classe of Institut Cancerologie de l’Ouest Rene Gauducheau, Nantes, France.
Cancer cells were detected by SLND in 139 subjects after NAC and surgery, and all of those patients underwent axillary lymph node dissection. Another 418 had no sentinel node involvement after NAC and surgery, and had adequate follow-up; among those, overall 3-year survival was 97.8% and 3-year disease-free survival was 94.8%,
“In this group of patients ... we found only one axillary relapse,” he said.
These rates are comparable to historical survival rates among those without axillary involvement who undergo axillary lymph node dissection rather than sentinel lymph node detection, and the findings suggest that women with no clinical signs of axillary involvement could be spared systematic lymphadenectomy, he said.
“The standard surgical treatment after neoadjuvant chemotherapy is breast cancer surgery and lymphadenectomy level 1 and 2, but since the [National Surgical Adjuvant Breast and Bowel Project] B-27 trial, we all know that after neoadjuvant chemotherapy there are not any involved nodes in 50%-58% of patients,” he said, adding that about half of all lymphadenectomies in these patients are therefore unnecessary.
That percentage increases to more than 70% in “the very specific situation of patients treated for HER2+ breast cancer with cytologically proved axillary metastases after neoadjuvant chemotherapy,” he said.
“So we know that there is a place for sentinel lymph node biopsy after neoadjuvant chemotherapy in order to avoid unnecessary lymphadenectomy,” he said.
However, the high false negative rate associated with SLND in this and in prior studies, including the first GANEA trial, remains a concern. In fact, the most recent guidelines stated that the proof was too weak to strongly recommend sentinel lymph node biopsy after NAC, he noted.
The GANEA 2 trial was performed in response to a call in those guidelines for additional studies to assess the long-term risks of this strategy.
Study subjects included patients with FIGO stage T1-T3 infiltrating breast cancer who were enrolled from 15 French institutions between July 2010 and February 2014. Those with inflammatory cancer, local relapse, contraindications for NAC, or interrupted NAC due to progressive disease were excluded.
Follow-up included a medical visit with clinical assessment every 6 months and annual mammography.
The findings suggest that in patients with no proof of node involvement before treatment, SLND “seems to be safe within the limits of the short-term follow-up of this study,” Dr. Classe said, noting that given the concerns about the false negative rate and the uncertainty about the clinical impact of that, this approach “is not proved to be a safe procedure outside of trials.”
The strategy will be further evaluated, with a focus on eliminating false negative results, in the GANEA 3 trial, he said.
Dr. Classe reported having no disclosures.