SAN ANTONIO – Axillary lymph node dissection is not warranted in patients with clinically node-negative breast cancer and micrometastases in the sentinel node, another randomized phase III clinical trial has found.
New 57-month follow-up data from the International Breast Cancer Study Group (IBCSG) trial 23-01 in breast cancer patients with minimal sentinel node involvement show no disease-free or overall survival differences between patients who underwent axillary dissection and those who did not, Dr. Viviana Galimberti reported at the San Antonio Breast Cancer Symposium.
This is consistent with the results of the American College of Surgeons Oncology Group (ACOSOG) Z0011 trial, which reported in February that it found no survival difference between early-stage breast cancer patients who underwent axillary lymph node dissection and those who did not after being found sentinel node positive on biopsy (JAMA 2011;305:569-75).
The IBCSG trial 23-01 randomized 934 patients from 27 centers to axillary dissection or no further axillary surgery. All of the patients had tumors no larger than 5 cm and minimal sentinel node involvement, defined as one or more micrometastatic (less than 2 mm) sentinel node were included in the analysis, said Dr. Galimberti of the European Institute of Oncology in Milan. Disease-free survival was the study’s primary end point, while overall survival and systemic disease-free survival were secondary end points, she said.
Of the 934 patients, 3 were excluded, including 2 patients in whom no tumor was found in the sentinel node and 1 patient who withdrew consent, Dr. Galimberti said. Of the remaining 931 patients in the intent to treat population, 17 of the 464 assigned to axial dissection did not receive it and 14 of the 467 assigned to no dissection did receive it, she said.
At study entry, mean patient age was 54 years, and more than half (56%) of the patients were postmenopausal. Regarding disease characteristics, 67% of the patients had tumors less than 2 cm, 7% had tumors 3 cm or larger, and 26% had grade 3 disease "Most of the tumors [89%] were estrogen receptor–positive and 75% were progesterone receptor–positive," Dr. Galimberti said. In the involved sentinel nodes, 67% of the patients had micrometastasis less than 1.0 mm, 29% had micrometastasis from 1.1-2.0, 2% had metastasis greater than 2.0, and 2% were unknown, she said.
In all, 96% of the patients underwent lymphoscintigraphy and evidence of one or two sentinel nodes was found in 85% of them, Dr. Galimberti reported. Previous excision biopsy was performed in 16% of the patients, and conservative surgery was the definitive treatment in three-quarters of the patients while 25% received mastectomy. Similar rates of adjuvant radiotherapy, hormonal therapy, and chemotherapy were seen in both groups, she said.
Long-term adverse events were more prevalent in the dissection group, with 18% experiencing sensory neuropathy, compared with 12% of those not undergoing dissection. Similarly, the respective rates of lymphedema were 13% and 4% and the respective rates of motor neuropathy were 8% and 3%, Dr. Galimberti reported.
The 5-year disease-free survival rates in the dissection and no dissection groups were 87.3% and 88.4%, respectively, said Dr. Galimberti. The 5-year overall survival rates were similar between both groups as well, at 97.6% in the dissection group and 98% in the no-dissection group.
"In total, there were 17 [3.7%] deaths among the patients who underwent dissection and 12 [2.6%] among those who did not," she said.
The lack of a difference between the groups for the primary end point of disease-free survival fulfilled the protocol-specified criterion for noninferiority. Indeed, Dr. Galimberti noted, "The 5-year disease-free survival of 88% in the patients who did not undergo dissection was much better than the 70% that was anticipated in the original plan," she said. The rate of reappearance of tumor in the undissected axilla was also unexpectedly low, at about 1%, she added.
"It seems likely that the results of the IBCSG Trial 23-01 and Z0011 will change clinical practice, allowing no axillary dissection in early breast cancer, especially when the sentinel node is minimally involved, to reduce [associated] complications with no adverse effect on survival," Dr. Galimberti concluded.
Dr. Galimberti reported having no relevant financial conflicts to disclose.