Abstract P4-02-17: Targeted axillary dissection after neoadjuvant chemotherapy
Authors: Steer Susanne , Große Regina , Zentgraf Holger , Thomssen Christoph 
Published: March 2020

Abstract
Background: Although neoadjuvant chemotherapy (PST) in early breast cancer patients is preferentially indicated according to the biological type of the disease, information about the involvement of the axillary lymph nodes (LNN.) is still required as prognostic factor, as response marker in PST, and to indicate adjuvant radiotherapy. Therefore, baseline clinically and ultrasound-guided examination of the axilla is mandatory; suspicious axillary LNN. should further be examined by core needle biopsy (CNB) und marked with a tagging clip before initiating PST. After PST, targeted axillary dissection (TAD), defined by resection of both sentinel lymph node and tagged node, can be performed to reduce the extent of the axillary intervention. The aim of the study was to evaluate the retrieval of the tagged LNN in a prospective manner after PST. In addition, we want to evaluate the axillary response rate after PST.
Methods: In 50 patients with suspicious axillary LNN who started PST between July 2016 and April 2019, ultrasound-guided core needle biopsy of the most prominent lymph node was performed in local anesthesia, and a tagging clip was inserted into the node (BIP-O-Twist-Marker, BIP biomedical instruments & products, Germany, Tuerkenfeld). After PST, the axilla was again evaluated by ultrasound and TAD was performed. Four patients with primarily histologically negative nodes underwent sentinel excision, only. In 10 patients, for persistent bulky nodes axillary dissection was performed. In 36 patients, the sentinel node, the tagged node and surrounding LNN. were removed. Prior to surgery, the clip-marked lymph node was localized by ultrasound, and a hook- wire for better retrieval was inserted.
Results: The evaluation includes 36 patients who started PST between July 2016 and April 2019 (Table 1). Prior to PST, four patients had no evidence of tumor in the CNB of the suspicious lymph node, confirmed by TAD after PST (median: 2 LNN; range 1-3). In 32 patients, lymph node tumor infiltration was found by the initial CNB. Thirteen of these patients had TAD (median: 5 LNN: range 4-10) and pathologic complete axillary response was described. In 19 patients, node-positive disease after PST was observed. TAD only was performed in five patients. Ten patients with clinically suspicious LNN underwent TAD and axillary dissection. Four patients underwent excision of the tagged node only (no sentinel) and axillary dissection. The median number of excised LNN was 11 (range 4 - 21), the median number of tumor-infiltrated LNN was 3 (range 1 - 10). In summary, in all patients the clip-tagged LNN was detected supported by hook-wire-marking before surgery, corresponding to a 100% retrieval rate. In 13 patients (41%) of 32 patients with tumor-infiltrated nodes before PST no residual tumor was found after PST. In patients with an axillary complete response after PST, less LNN were removed than in patients without an axillary complete response. To date, no locoregional recurrence was observed.
Conclusion: Technically, TAD is feasible and can be performed with a high retrieval rate. Particularly in patients with low tumor load in the axilla and clinically complete response, TAD may aid to reduce the extent of axillary dissection.
Results of TAD after PST in relation to the initial lymph node status.
Initial lymph node statusClinically suspect, CNB negative (N=4)Tumor-infiltration (CNB positive) (N=32)Lymph node infiltration after PSTNo infiltrationComplete remission (N=13)Residual disease (N=19)Retrieved lymph nodes (by TAD)41319Excised LNN. [median (range)]2 (1-3)5 (4-10)11 (4-21)Tumor-infiltrated LNN [median (range)]003 (1-10)
Citation Format: Susanne Steer, Regina Große, Holger Zentgraf, Christoph Thomssen. Targeted axillary dissection after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-02-17.