Abstract PS1-44: Impact of a standardized protocol for management of axilla after neoadjuvant chemotherapy in breast cancer patients at a cancer center

Abstract

Abstract Background: Axillary lymph node status is one of the most important prognostic factors in breast cancer (BC). Neoadjuvant Chemotherapy (NACT) has been indicated for locally advanced tumors, and for HER2-positive and triple negative tumors larger than 2.0 and 1.0 cm, respectively, regardless of axillary status. This approach allows to assess biological response of the tumor, predicting prognosis and may permit more conservative surgeries in breast and axilla. However, there is no consensus about the best approach on management of axilla after NACT. Objective: To evaluate the rate of axillary downstaging after NACT in BC patients using a standardized protocol with a clip marker placement on positive lymph nodes prior to chemotherapy at a Cancer Center. Methods: This single-center, Institutional Review Board (IRB)-approved, retrospective study evaluated 471 BC patients who underwent NACT from January/2014 to December/2018. All included patients were evaluated for histological type, clinical T and N stages before NACT, modality of breast surgery (mastectomy vs. lumpectomy), type of axillary dissection (Axillary Lymph Node Dissection [ALND], sentinel lymph node biopsy [SLNB], or SLNB followed by ALND), placement or not of a clip marker in axillary lymph nodes before NACT, reason for the ALND and the pathological response by residual cancer burden (RCB) criteria. Patients were divided in two groups, before and after institution of a standardized protocol for axillary management after NACT in January/2017, which consists of: (1) biopsy of clinically suspect axillary lymph nodes before NACT, and placement of a clip marker in one positive lymph node in patients with 1-2 suspected lymph nodes (N1); (2) SLNB after NACT using blue dye and radioactive isotope injection; (3A) in the presence of clip marker in an axillary lymph node, confirmation of its extraction is performed through radiography of the surgical specimen and, (3B) in the absence of clip markers on axillary lymph nodes, removal of at least 03 sentinel lymph nodes should be performed; (4) no further axillary dissection is performed if all SLN are negative on frozen section analysis; any residual lymph node disease and/or absence of previously placed clip marker on SLNB specimen indicate ALND.Results: Patients’ mean age was 47 years (range 24-87 years), 67.2% (n=316) were cT2-T3, 83.5% (n=393) cN+ (N1 and N2), 62.6% (n = 295) had mastectomy. ALND was performed in 64.7% (n=303) patients, SLNB in 33.3% (n=156) and SLNB followed by ALND in 1.9% (n=9). In the subgroup of N+ patients (n=385), it was possible to perform SNB in 25.6% (n=98). 165 of 471 patients (35%) were included in standardized protocol for axillary management; the rate of SLNB in N+ patients was statistically higher in this group when compared to patients treated before the implementation of the protocol (34.4% vs. 22.8%; p=0.025).Conclusion: The results of the present study demonstrate a significant increase in sparing ALND after the implementation of a standardized protocol for management of axilla after NACT. However, further multi-institutional studies are still needed to support its widely adoption, as well as clinical trials to assess overall and disease-free survival in those patients who had omitted ALND after NACT. Citation Format: Marina de Paula Canal, Caroline Rocha, Marina Sonagli, Almir Bitencourt, Solange Sanches, Monique Tavares, Cynthia Osório, Fabiana Baroni Makdissi. Impact of a standardized protocol for management of axilla after neoadjuvant chemotherapy in breast cancer patients at a cancer center [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-44.