P02 Is it still necessary to perform sentinel lymph node biopsy in breast cancer patients with negative axillary ultrasound in post-Z0011 era? – retrospective analysis

Introduction/Background According to the results of ACOSOG Z0011 trial, there is no need to complete axillary dissection in patients after breast conserving surgery and one or two positive sentinel lymph nodes (SLN). Because axillary ultrasound has high sensitivity and specificity in detection of macrometastases in axilla, chance of missing more than two macrometastases is supposed to be low. Aim of this trial was to assess the number patients with negative axillary ultrasound who had more than two infiltrated SLNs in definitive histology (and did not fulfill the inclusion criteria for Z0011 trial) and the number of patients in whom axillary macometastases would be missed if SLN biopsy (and axillary dissection) was not performed. Methodology Breast cancer patients with tumors up to 5cm and no metastases on axillary ultrasound treated in our institution in 2016 were included into the retrospective analysis. Macrometastsis in SLN was an indication for axillary dissection. Number of patients with more than two macrometastases in SLNs and total number of patients with nodal macrometastases were evaluated. Results There were 87 patients enrolled into the trial - 11 of them had macrometastases in SLNs: 10 patients had one and 1 had three macrometastases in SLNs. All these 11 patients were subject to axillary dissection - in one patient there were 4 more macrometastases in other axillary lymph nodes. Conclusion 1 patient (1%) did not fulfill the inclusion criteria of Z0011 trial and thus SLN biopsy would change the management. If SLN biopsy wasn’t performed, macrometastases in 11(13%) patients would be missed. Of these, one had 3 and one had 5 macrometastases. Nowadays it is not clear if these missed axillary nodal macrometastases are of any impact on oncological outcome. Future prospective trials will bring more evidence on this topic. Disclosure Nothing to disclose.