Long-term follow-up confirms the oncologic safety of sentinel node biopsy without axillary dissection in node-negative breast cancer patients.

The sentinel node biopsy (SNB) technique for breast cancer was introduced in the early 1990s as a less invasive means of axillary staging than standard axillary dissection (ALND). There have been a multitude of studies performed to evaluate the accuracy of SNB, and a recent meta-analysis demonstrated that the status of the sentinel lymph node (SLN) can accurately predict the status of the axillary basin with an average false-negative rate of 7.3%. Experienced surgeons achieve even lower false-negative rates, ranging from 0% to 5%. Before definitive evidence from randomized controlled trials was available to demonstrate its long-term safety, SNB was rapidly accepted by the surgical and oncological communities. This occurred because the procedure proved to be an accurate diagnostic test to assess the axillary lymph nodes. Each surgeon could determine his or her own accuracy by performing SNB and comparing the results to ALND in the same patient. A randomized trial is not necessary to test the accuracy of a diagnostic test, and SNB has now replaced ALND as the standard of care for axillary staging in patients with early breast cancer. A randomized trial is necessary to determine the safety and therapeutic implications of a new procedure. A number of randomized trials specifically addressed shortand long-term morbidity of SNB compared with ALND. These trials showed that the morbidity of SNB is less than that of ALND. However, there are only a few studies that report data on the long-term outcome of SNB, and the follow-up in these reports is limited. In this issue of Annals of Surgery the study by the excellent group led by Veronesi, is the first randomized trial to report 10-year follow-up for SNB with or without routine completion ALND. The trial was a single institution study involving 516 patients with breast tumors of 2 cm or less in size, who were randomly assigned to either SNB followed by ALND or SNB with ALND only if the SLN contained metastatic disease. The initial results from this trial were published in 2003, where the efficacy and safety of the SNB procedure were validated. In their earlier report, they demonstrated the false-negative rate of the SNB procedure to be 8.8%, with an overall accuracy of 96.9%. They found that there was less pain and greater arm mobility in patients who had SNB alone compared with those who had ALND. These results are similar to the findings reported from other randomized trials that specifically evaluated efficacy and side effects. With a mean follow-up of 46 months, the 2003 report demonstrated that short-term survival was not compromised in those who had a negative SNB without ALND. The authors then provided an update on this trial in 2006, where after a median follow-up of 79 months, there were 34 breast cancer-related events, 16 in the SNB arm with one axillary recurrence and 18 in the ALND arm with no axillary recurrences (P 0.6). The 5-year overall survival was 98.4% in the SNB group and 96.4% in the ALND group. These findings are similar to results of the other randomized trials with shorter follow-up that evaluated the disease-free and overall survival of SNB with and without ALND. Zavagno et al conducted a multicenter trial of 697 patients with tumors less than or equal to 3 cm in diameter. After a mean of 56 months of follow-up, there were 29 locoregional events in the SNB group and 22 events in the ALND group. They found no difference between the 2 groups with respect to disease-free or overall survival. Canavese et alcompared SNB with and without ALND in a much smaller cohort of 115 patients followed up for a median of 66 months. There were 12 events in the ALND arm with one axillary recurrence and 10 events in the SNB arm with no axillary recurrences. The authors did not demonstrate a difference in disease-free or overall survival between the 2 groups. In the current report by Veronesi et al, an update of their randomized trial is provided with a median follow-up of 102 months. There were a total of 49 breast cancer-related events, 23 in the SNB arm and 26 in the ALND arm (P 0.52). There was no difference between the 2 groups with respect to disease-free survival (89.9% in the SNB arm vs. 88.8% in the ALND