According to updated data of the International breast cancer study group (IBCSG) trial 23-01 presented by Viviana Galimberti, MD (International Breast Cancer Study Group) during the 2011 CTRC-AACR San Antonio Breast Cancer Symposium, axillary dissection can be avoided in the management of patients with early breast cancer. For patients with a metastatic sentinel node, axillary dissection is standard treatment to achieve optimal locoregional control. However, for many patients, the sentinel node is the only positive node and for patients with minimal sentinel node involvement, axillary dissection may be overtreatment.
In this light, the IBCSG trial 23-01 was designed to determine whether axillary dissection is necessary in patients with minimal sentinel node involvement. Patients that were eligible for the study were first registered after which patients with sentinel node involvement were randomly assigned to undergo axillary dissection or not. The trial started in April 2001 and had an accrual target of 1,960 patients. However, in February 2010, the study closed earlier with 934 randomized patients from 27 centers. The primary reasons for this early closure were that the projected time to complete accrual was too long, and that the aggregated event rate at 30 months median follow up was much lower than anticipated. The presented data were based on an intent-to-treat population of 931 patients with a median follow-up of 57 months.
The disease free survival was comparable for patients who underwent axillary dissection or not (no AD vs. AD, 88,4% vs. 87%; HR[95%CI]: 0.87[0.67-1.12]; p=0.48). “Moreover,” Galimberti said, “ this disease free survival was much higher than what was anticipated for in the initial plan.” Interestingly, researchers reported an unexpectedly low rate of tumor recurrence in the undissected axilla (less than 1%). With respect to overall survival, both study groups performed almost identical with a five-year survival rate of approximately 98%.
These findings are consistent with the results of the ACOSOG Z0011 study, published earlier this year (JAMA 2011;305(6):569-75). This study with 856 breast cancer patients did not find any difference in any of the endpoints between patients who underwent axillary dissection or not after 6.3 years of follow-up. “It is likely that the results of IBCSG 23-01 and ACOSOG Z0011 will change the clinical practice. Based on these data, axillary dissection should be avoided in patients with early breast cancer, especially in those patients with a minimally involved sentinal node.”
Galimberti concluded. “Such patients can be spared the complications associated with axillary dissection without adverse effects on survival.”