Long-term Data Support Less Surgery in Breast Cancer

Pam Harrison

September 11, 2018

The current practice of not performing an axillary lymph node dissection in patients with early breast cancer who have minimal or moderate disease in the sentinel nodes continues to be upheld after 10 years of follow-up from the International Breast Cancer Study Group (IBCSG) 23-01 trial.

At a median follow-up of 5 years, IBCSG 23-01 trialists previously reported no difference in disease-free survival between patients with breast cancer and one or more micrometastatic (≤2 mm) sentinel nodes who underwent axillary dissection and those who did not. There were also no between-group differences in overall survival or recurrence rates at 5 years.

In the latest findings from the same trial, disease-free survival at 10 years was 76.8% in patients who did not undergo axillary dissection compared with 74.9% in those who did undergo it (P = .0024 for noninferiority), Viviana Galimberti, MD, European Institute of Oncology, Milan, Italy, and multicenter IBCSG colleagues report. The long-term results were published online September 5 in the Lancet Oncology.

"The 10-year results of the IBCSG 23-01 trial provide important, additional level-1 evidence that omitting axillary dissection when the sentinel nodes contain only micrometastases is safe, supporting the avoidance of potentially serious and chronic sequelae of this surgery in women with early breast cancer," the investigators state.

"These results support the clinical practice of omitting axillary dissection when disease burden in the sentinel nodes is moderate," they affirm.

Study Design

IBCSG 23-01 was a randomized controlled noninferiority trial comparing no axillary dissection with axillary dissection in patients with breast cancer and sentinel-node micrometastases.

"Patients receiving breast-conserving surgery were required to undergo radiotherapy to the residual breast, which could be either conventional whole-breast irradiation or partial-breast irradiation given intra-operatively," Galimberti and colleagues write.

Ninety-one percent of patients in the IBCSG 23-01 trial underwent breast-conserving survey and only 9% had mastectomy, the authors point out.

A total of 931 patients comprised the intention-to-treat population: 467 were assigned to the no axillary dissection group and 464 underwent axillary node dissection.

At a median follow-up of 9.7 years, "the proportion of patients with local recurrences was similar in the two groups," the investigators report — although rates of regional events were slightly higher in women who did not undergo axillary dissection even though rates were very low in both groups.

The cumulative incidence of breast cancer events was also almost identical in both groups, and rates of ipsilateral axillary failures were also low regardless of the group to which participants were assigned.

Table. Ten-Year Event Rates in IBCSG 23-01

Event No Axillary Dissection (%) Axillary Dissection (%)
Breast cancer events 17.6 17.3
Local recurrences 3 3
Regional events 2 1
Ipsilateral axillary failures 2 <1

 

At 10 years, 90.8% of patients not undergoing axillary node dissection were still alive, as were 88.2% of those assigned to the axillary dissection group.

As the authors note, they did not continue to monitor patients for long-term surgical adverse events after year 5. As a result, the 10-year event rates are almost identical to those presented at 5 years.

At a median follow-up of 9.7 years, 13% of patients allocated to the no axillary dissection group reported any grade of sensory neuropathy vs 19% of those who underwent axillary dissection.

Lymphedema of any grade was also reported by 4% of patients who did not undergo axillary dissection compared with 13% of those who did. Motor neuropathy of any grade was reported by 3% and 9% of patients, respectively.

No grade 3 or 4 surgical adverse events of any kind occurred in the no axillary dissection group.

Accompanying Editorial

In an accompanying editorial, Henry Kuerer, MD, PhD, from the University of Texas MD Anderson Cancer Center in Houston, points out that up to the early 2000s, "almost all women throughout the world presenting with clinically node-negative invasive breast cancer routinely received complete axillary lymph node dissection."

This procedure is frequently associated with lymphedema, shoulder dysfunction, and pain that often persists for years after the surgery has been done and can significantly affect quality of life for breast cancer survivors.

"The development of sentinel lymph node biopsy for breast cancer using a radiocolloid lymphatic tracer and blue dyes occurred in the mid-1990s," Kuerer notes.

This quality of life–altering procedure has largely eliminated the necessity of doing an axillary lymph node dissection when minimal disease is detected in the sentinel lymph nodes, he points out.

Although it took several single-center and multicenter national and international trials to get to this point, "in the USA, there is no longer any controversy regarding the appropriate management of micrometastases or macrometastases identified in one or two nodes in patients receiving breast conservation therapy," Kuerer writes.

"Findings [from the current study] add increasing high-quality evidence that no axillary lymph node dissection is not inferior to axillary lymph node dissection for patients with micrometastases 10 years after treatment, with respect to both the primary endpoint of disease-free survival and overall survival," he reaffirms.

IBCSG 23-01 was supported by the centers that enrolled the women and the International Breast Cancer Study Group, which is partly funded by the Swiss Group for Clinical Cancer Research; the Swiss Cancer League/Cancer Research Switzerland/Oncosuisse, Frontier Science and Technology Research Foundation; The Cancer Council Australia; The Australian New Zealand Breast Cancer Trials Group (National Health Medical Research Council); The Swedish Cancer Society; and The Foundation for Clinical Cancer Research of Eastern Switzerland. Galimberti has disclosed no relevant financial relationships. Some co-investigators report industry ties, which are listed in the publication. Kuerer has disclosed no relevant financial relationships.

Lancet Oncol. Published online September 5, 2018. Abstract

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