Preliminary findings of the International Breast Cancer Study Group (IBCSG) 23-01 trial¹ show no benefit for axillary lymph node dissection in patients with only minimally involved sentinel nodes, thereby supporting the results of the American College of Surgeons Oncology Group (ACOSOG) Z0011 trial.² IBCSG 23-01 results were reported at the 2011 San Antonio Breast Cancer Symposium by Viviana Galimberti, MD, of the European Institute of Oncology in Milan, Italy.

“It seems likely that IBCSG 23-01 and ACOSOG Z0011 will change clinical practice, allowing no axillary lymph node dissection in early breast cancer, especially when the sentinel node is minimally involved,” Dr. Galimberti said. “This will reduce complications from axillary dissection without an adverse effect on survival.”

Design and Data

IBCSG 23-01 was designed to determine whether axillary lymph node dissection is necessary in patients with tumor ≤ 5 cm and minimal sentinel node involvement, defined as one or more micrometatastic sentinel nodes (≤ 2 mm). On permanent or frozen samples, each node was entirely sectioned at 50- to 100-μm intervals, and all sections were examined. Patients were randomly assigned to have axillary lymph node dissection or sentinel node biopsy only.

The intent-to-treat population consisted of 931 patients, and after a median follow-up of 57 months there were 98 events. Approximately two-thirds had tumors < 2 cm, more than 80% were estrogen receptor–positive, 90% underwent breast-conserving surgery and radiotherapy, and two-thirds had hormonal therapy without chemotherapy.

The 5-year disease-free survival rate was 87.3% in patients undergoing axillary lymph node dissection and 88.4% for those with sentinel node biopsy alone (P = .48). Regional recurrence was observed in one patient (0.2%) and five patients (1.1%), respectively. The 5-year overall survival rate was 98% in each arm.

Study Implications

“There was no difference in the primary endpoint, disease-free survival, which fulfilled the protocol-specified criterion for noninferiority,” Dr. Galimberti reported. She added that disease-free survival was higher (88%) than anticipated (70%), and there was an unexpectedly low rate of reappearance of tumor in the undissected axilla (1.1%).

“This is an important trial, but our results are preliminary and we must wait for the full analysis,” she said. “Nevertheless, we have robust data suggesting that from now on, we may not need to do axillary dissection in patients with minimally involved sentinel nodes.” ■

Disclosure: Dr. Galimberti reported no potential conflicts of interest.

References

1. Galimberti V, Cole BJ, Zurrida S, et al: Update of International Breast Cancer Study Group trial 23-01 to compare axillary dissection versus no axillary dissection in patients with clinically node negative breast cancer and micrometastases in the sentinel node. 2011 San Antonio Breast Cancer Symposium. Abstract S3-1. Presented December 8, 2011.

2. Giuliano AE, Hunt KK, Ballman KV, et al: Axillary dissection vs no axillary dissection in women with invasive breast cancer and sentinel node metastasis. JAMA 305:569-575, 2011.