By Kate O’Rourke

San Antonio—Doctors now have additional evidence that axillary lymph node dissection (ALND) does not add benefit to sentinel lymph node resection in clinically node-negative breast cancer patients with minimal sentinel node involvement. These results come from an update of the Phase III International Breast Cancer Study Group (IBCSG) trial 23-01. The study was reported at the San Antonio Breast Cancer Symposium (SABCS; abstract S3-1).

“Our findings are consistent with those of the ACOSOG Z-11 trial,” said Viviana Galimberti, MD, of the European Institute of Oncology in Milan, referring to the study conducted by the American College of Surgeons Oncology Group (ACOSOG). That randomized trial, first presented at the 2010 annual meeting of the American Society of Clinical Oncology, showed no benefit from ALND in clinically node-negative patients with one or two positive sentinel nodes. Since then, surgeons have gradually been adopting the more conservative approach to surgery. Dr. Galimberti said the two trials together should change clinical practice.

Patients eligible for the IBCSG 23-01 trial had clinically node-negative breast tumors that were 5 cm or smaller as well as minimal sentinel node (SN) involvement, defined as one or more micrometastatic (2 mm) SNs. Patients were not included if they had pure ductal carcinoma in situ, previous systemic therapy for breast cancer, chemoprevention within the past year, distant metastases, palpable axillary lymph nodes and a previous or concomitant malignancy.

Patients were randomized to either receive ALND or not to receive ALND. The arms were well balanced in terms of tumor size, tumor grade, tumor histology, estrogen and progesterone receptor status and local and systemic treatment.

At SABCS, the researchers discussed outcomes of 931 patients. With a median follow-up of 57 months, no difference was identified between the two arms in the primary end point of disease-free survival (88.4%, no ALND vs. 87.3%, ALND; hazard ratio, 0.87; 80% confidence interval, 0.67-1.12; below noninferiority boundary of 1.25; P=0.48) and for the secondary end point of overall survival (98.0%, no ALND vs. 97.6%; P=0.35).

As expected, adverse events were more frequent in patients in the ALND arm than in the non-ALND group, including sensory neuropathy (18% vs. 12%), lymphedema (13% vs. 4%) and motor neuropathy (8% vs. 3%).

Both IBCSG 23-01 and ACOSOG Z-11 met less than half of their targeted accrual goals, reflecting the difficulties in conducting a trial that challenges conventional practice; however, the results demonstrate the value of such trials.

“I hope everyone will go home and stop doing axillary dissections on women with clinically negative nodes and a positive sentinel node,” said Laura Esserman, MD, professor in the Departments of Surgery and Radiology and affiliate faculty at the Institute for Health Policy Studies, and director of the Carol Franc Buck Breast Care Center, University of California, San Francisco. “More is not better—that is what the data show.”