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Sentinel node biopsy noninferior to axillary lymph node dissection for node-positive breast cancer
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CHICAGO — Long-term survival outcomes from the ACOSOG Z0011 trial supported the initial finding of noninferiority for sentinel node biopsy compared with axillary lymph node dissection in select patients with sentinel node–positive breast cancer, according to 10-year follow-up data presented at the ASCO Annual Meeting.
The early results of ACOSOG Z0011 showed that treatment with sentinel node biopsy, whole-breast irradiation and adjuvant systemic therapy conferred noninferior OS and DFS compared with axillary lymph node dissection.
“This study was open from May of 1999 until December of 2004, when it closed early due to low enrollment,” Armando E. Giuliano, MD, FACS, executive vice chair of surgical oncology at Cedars-Sinai Medical Center in Los Angeles and associate director of surgical oncology at the Samuel Oschin Comprehensive Cancer Institute, said during his presentation. “Despite the low enrollment, there was a statistically significant noninferiority between axillary lymph node dissection and sentinel lymph node dissection. Like most breast cancer studies, however, it contained mostly postmenopausal women with hormone receptor–positive tumors — a group known to have late recurrences — and the study was criticized for short follow-up.”
Researchers randomly assigned women with clinically node-negative disease, as well as one or two sentinel nodes with metastases detected through hematoxylin and eosin staining, to sentinel node biopsy alone (n = 446) or with axillary lymph node dissection (n = 445). All women then received whole-breast irradiation and systemic therapy.
Women assigned sentinel node biopsy had a median of two lymph nodes removed, compared with a median of 17 lymph nodes for patients assigned axillary lymph node dissection. Significantly more women assigned axillary lymph node dissection had three or more lymph nodes removed (17.6% vs. 5%; P < .001).
The researchers did not record a significant difference in local or regional recurrences after a median follow-up of 9.25 years. Two nodal recurrences occurred in the axillary lymph node dissection arm, compared with five nodal recurrences among women assigned sentinel node biopsy.
Women assigned sentinel node biopsy had a 10-year locoregional RFS rate of 94.1%, compared with 93.2% for axillary lymph node dissection.
The 10-year OS rate was 86.3% for sentinel node biopsy and 83.6% for axillary lymph node dissection. The 10-year DFS rate was 80.3% for sentinel node biopsy and 78.3% for axillary lymph node dissection.
Eleven percent of patients did not receive radiation, and the researchers noted differences in radiation delivery in 228 radiation records, including supraclavicular field (18.9%) and high tangents (50%). Variations in radiation delivery were distributed equally across study arms.
“This study provides data that do not support axillary lymph node biopsy alone, and shows that sentinel lymph node biopsy provides excellent 10-year disease control and survival,” Giuliano said. “The routine use of axillary lymph node dissection should be abandoned.” – by Cameron Kelsall
Reference:
Giuliano AE, et al. Abstract 1007. Presented at: ASCO Annual Meeting; June 3-7, 2016; Chicago.
Disclosure: Giuliano reports no relevant financial disclosures. Please see the abstract for a list of all other researchers’ relevant financial disclosures.
Perspective
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Anees B. Chagpar, MD, MSc, MBA, MPH, FACS, FRCS(C)
ACOSOG Z0011 was a landmark trial that looked at whether completion of axillary lymph node dissection was necessary for patients who had one or two positive sentinel nodes, who were undergoing partial mastectomy followed by whole-breast irradiation. The idea was that whole-breast radiation therapy covers the lower two-thirds of the axilla. For patients with minimal disease, there was an idea that sentinel node biopsy and radiation therapy was sufficient to clear the axilla of any residual metastases, such that axillary node dissection was not mandated. This would spare patients the morbidities associated with that procedure.
At the time that the results were originally released, in 2010, the study was criticized for a number of reasons. First, it was underpowered, in the sense that it did not meet its accrual target. Second, there was a suggestion of selection bias that seemed to be evident in the patients treated in the trial. There was also criticism over the lack of long-term follow-up.
This year at ASCO, Armando E. Giuliano, MD, FACS, presented the 10-year follow-up data, and it really bore out what we already knew in terms of the initial data. The finding that there is no survival difference between the procedures is something that was really well known, even looking back to data from the NSABP B-04 trial data, which showed that axillary lymph node dissection did not provide survival benefits. Its main benefit is for staging — that is, to learn how many nodes are positive — and for local control.
The important finding in the updated data is that we continue to see very low rates of locoregional failure in both groups, such that we can feel more comfortable avoiding axillary lymph node dissection in these patients.
Something else that came out in the study — which was another initial critique of the trial — was with regard to the addition of a third field of radiation, or the use of high tangent radiation. These would have been deviations from the protocol, and it caused a lot of people to criticize the initial result when they came out, because these protocol deviations were not analyzed. It was thought that the low incidence of locoregional control could be associated with the deviations. What Giuliano showed in his presentation was that the protocol deviations were equally distributed between the two groups, and thus would not lead disproportionately to a lower rate of locoregional recurrence in the sentinel bode biopsy group.
This has given us all a bit more confidence in the Z0011 trial data. To be honest, many surgeons have already changed their practices based on the initial findings, but this can give us all more confidence in that practice change.
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