Axillary Management Research Articles

Breast cancer related lymphoedema: a review of contemporary preventive strategies.

Secondary lymphoedema remains an incurable long-term complication of breast cancer treatment. Prevention is our best chance against this debilitating condition. Strategies for selective de-escalation of oncological therapies have continued to evolve over the last few decades to reduce the incidence of this feared complication. In this manuscript we first review the current strategies in de-escalation of axillary treatment. We then review the current evidence for immediate lymphatic reconstruction in those high-risk patients who cannot be spared from more aggressive axillary management.

Nodal Burden and Oncologic Outcomes in Patients With Residual Isolated Tumor Cells After Neoadjuvant Chemotherapy (ypN0i+): The OPBC-05/ICARO Study.

The nodal burden of patients with residual isolated tumor cells (ITCs) in the sentinel lymph nodes (SLNs) after neoadjuvant chemotherapy (NAC) (ypN0i+) is unknown, and axillary management is not standardized. We investigated rates of additional positive lymph nodes (LNs) at axillary lymph node dissection (ALND) and oncologic outcomes in patients with ypN0i+ treated with and without ALND. The Oncoplastic Breast Consortium-05/ICARO cohort study (ClinicalTrials.gov identifier: NCT06464341) retrospectively analyzed data from patients with stage I to III breast cancer with ITCs in SLNs after NAC from 62 centers in 18 countries. The primary end point was the 3-year rate of any axillary recurrence. The rate of any invasive recurrence was the secondary end point. In total, 583 patients were included, of whom 182 (31%) had completion ALND and 401 (69%) did not. The median age was 48 years. Most patients (74%) were clinically node-positive at diagnosis and 41% had hormone receptor-positive/human epidermal growth factor receptor 2-negative tumors. The mean number of SLNs with ITCs was 1.2. Patients treated with ALND were more likely to present with cN2/3 disease (17% v 7%, P < .001), have ITCs detected on frozen section (62% v 8%, P < .001), have lymphovascular invasion (38% v 24%, P < .001), and receive adjuvant chest wall (89% v 78%, P = .024) and nodal radiation (82% v 75%, P = .038). Additional positive nodes were found at ALND in 30% of patients, but only 5% had macrometastases. The 3-year rates of any axillary and any invasive recurrence were 2% (95% CI, 0.95 to 3.6) and 11% (95% CI, 8 to 14), respectively, with no statistical difference by type of axillary surgery. The nodal burden in patients with ypN0(i+) was low, and axillary recurrence after ALND omission was rare in patients selected for this approach. These results do not support routine ALND in all patients with ypN0(i+).

Comprehensive Axillary Management of Clinically Node-Positive (cN+) Breast Cancer Patients: A Narrative Review on Neoadjuvant Chemotherapy.

In breast cancer (BC) patients, axillary management has undergone major improvements over the last few years, and efforts to identify the optimal strategy for the management of axillary surgery are still ongoing. In current clinical practice, women with clinically node-positive (cN+) BC usually receive neoadjuvant chemotherapy (NACT) with the aim of reducing the extent of primary disease and, thus, allowing for axillary-conservative surgery. Remarkably, after NACT, up to one out of three patients achieves an axillary pathologic complete response, which, in turn, is associated with a more favorable prognosis than residual axillary disease. However, NACT is not without drawbacks, as NACT-associated inflammation can damage lymphatic vessels. Furthermore, varying degrees of response may occur in the axillary lymph nodes, increasing the false negative rate for sentinel biopsy. At present, there is no consensus on the optimal approach in patients with cN+ BC undergoing NACT, although multidisciplinary management seems to be recommended. This narrative review provides a comprehensive overview of axillary management in cN+ BC patients undergoing NACT. It uses a multidisciplinary approach that encompasses the oncological management perspectives, as well as surgical and chemotherapeutic viewpoints.

Prediction of non-sentinel lymph node metastases in T1–2 sentinel lymph node-positive breast cancer patients undergoing mastectomy following neoadjuvant therapy

BackgroundAxillary lymph node dissection (ALND) is the standard axillary management for breast cancer patients with positive sentinel lymph node biopsy (SLNB) after neoadjuvant therapy. Nevertheless, when that happens, the frequency of additional positive nodes is not properly evaluated. We aim to develop a prediction model to assess the frequency of additional nodal disease after a positive sentinel lymph node following neoadjuvant therapy.MethodsWe retrospectively analyzed the ultrasound and clinicopathological characteristics of breast cancer patients with 1–3 positive sentinel lymph nodes (SLN) undergoing mastectomy after neoadjuvant therapy (NAT) at our institution, and performed univariate and multivariate logistic analyses to confirm the factors affecting non-SLN metastasis. These factors were included to establish a nomogram, and the area under receiver operating characteristic curve (AUC) and decision curve analysis (DCA) were utilized to assess the validity of this model.ResultsA total of 126 breast cancer patients were ultimately included in our study, 38 (53.5%) patients were diagnosed with non-SLN metastases of all 71 patients in training set. The results of multifactorial logistic analysis suggested that lymph node metastasis ratio (LNR), short axis of lymph node and progesterone receptor (PR) were strongly associated with non-SLN metastasis. We established a nomogram using the above three variables as predictors, which yielded an area under the curve of 0.795, and validated with a favorable AUC of 0.876.ConclusionThe nomogram we constructed can accurately predict the likelihood of non-SLN metastasis in our patients with 1–3 positive SLN after NAT, which may help guide decision making regarding axillary management.

ThP1.2 - Management of breast cancer sentinel lymph node macrometastasis in the axilla; audit of current unit practice and evaluation of factors that influence patient management

Abstract Aims Detection of sentinel lymph node (SLN) macrometastasis for breast cancer no longer mandates further axillary surgery. Association of Breast Surgery (ABS) guideline provides recommendation to optimise patient management. It also acknowledges management uncertainties in specific patient groups. We aimed to examine our unit practice against national guideline and evaluate potential factors that influence axillary management. Methods Retrospective analysis of prospectively maintained electronic database determined clinico-pathological characteristics on patients diagnosed with SLN macrometastasis (n=127) at the Leeds Breast Unit (2020-2022). Axillary management was compared against ABS guideline. Results 56 (44.1%) received completion axillary node clearance (cANC), 37 (29.1%) axillary radiotherapy (aRT), and 34 (26.8%) no further axillary treatment. 80.3% had one macrometastasis. As per guideline, all patients who had &amp;gt;3 macrometastasis (n=10) underwent cANC. Type of breast surgery (mastectomy vs. breast conserving surgery; BCS) did not affect further axillary treatment rate (76.7% vs. 70.1%). Type of further axillary treatment varied with cANC commonest for mastectomy patients (78.3%) and aRT commonest for BCS patients (57.4%). In contrast to the guideline, 58% of post-menopausal BCS patients with ER+HER2- T1 tumours (n=12) received further axillary treatment. Where guideline stated management uncertainty, further axillary treatment was frequent; pre-menopausal patients (82%), T2 tumours (73%), lymphovascular invasion (74%), and extranodal spread (77%). Conclusion Our unit’s SLN macrometastasis management is mostly in line with national guideline but further work is required to avoid overtreatment. Where management uncertainty exists, patients commonly received further axillary treatment. Further research is required in these patient groups to optimise axillary management.

Omission of Axillary Lymph Node Dissection in Patients with Residual Nodal Disease After Neoadjuvant Chemotherapy.

Axillary management after neoadjuvant chemotherapy (NAC) is evolving but axillary lymph node dissection (ALND) remains the standard of care for patients with residual nodal disease. The results of the Alliance A011202 trial evaluating the oncologic safety of ALND omission in this cohort are pending but we hypothesize that ALND omission is already increasing. The National Cancer Database was queried to identify patients diagnosed with cT1-3N1M0 breast cancer who underwent NAC and had residual nodal disease (ypN1mi-2) from 2012 to 2021. Temporal trends in omission of completion ALND were assessed annually. Multivariable logistic and Cox regression models were used to identify factors associated with ALND omission and overall survival (OS), respectively. A total of 6101 patients were included; the majority presented with cT2 disease (57%), with 69% HER2+, 23% triple-negative, and 8% hormone receptor-positive/HER2-. Overall, 34% underwent sentinel lymph node biopsy (SLNB) alone. Rates of ALND were the lowest in the last 4years of observation. After adjustment, treatment at community centers (vs. academic) and lower pathologic nodal burden were associated with omission of ALND. ALND omission was associated with a higher unadjusted OS (5-year OS: 86% SLNB alone vs. 84% ALND; log-rank p=0.03), however this association was not maintained after adjustment. Despite the impending release of the Alliance A011202 results, omission of ALND in patients with residual nodal disease after NAC is increasing. This practice appears more prominent in community centers and in patients with a lower burden of residual nodal disease. No association with OS was noted.

Accessory Axillary Breast Management: Is Primary Skin Excision Necessary?

AbstractAxillary breasts are a common entity with a reported incidence of 2 to 6% in women and 1 to 3% in men. They are more common amongst Asians than Caucasians, namely amongst South East Asians and Indians, with the highest incidence amongst Japanese. While modalities like CoolScupting™, Kybella™ injections, and BodyTite™ have been used by surgeons for management of axillary breasts, the most effective treatment for this condition remains surgical management involving a combination of liposuction of the axillary breast with excision of the gland and skin. In the author's experience, primary skin excision always leaves a long visible scar that widens over time, at times leading to contractures and restricted axillary movements even when closure looks tension free on the table. Any skin excess is best dealt with secondarily. The author uses a modified protocol without any primary skin excision in axillary breast management to achieve excellent results with minimal scars.

246P Axillary management and outcomes after neoadjuvant endocrine therapy in the randomized PELOPS trial

246P Axillary management and outcomes after neoadjuvant endocrine therapy in the randomized PELOPS trial

Nodal Response and Survival After Neoadjuvant Endocrine Therapy in Hormone Receptor-Positive Breast Cancer: 20-Year Experience from a Single Institution.

Axillary response to neoadjuvant endocrine therapy (NET) for the treatment of hormone receptor-positive breast cancer (HR+ BC) is not well-described. This study was designed to characterize nodal response after NET. Patients receiving NET followed by curative intent surgery at a comprehensive cancer center from 1998 to 2022 in a prospectively collected registry were included. Patients with distant metastasis were excluded. Primary outcome was nodal pathologic complete response (pCR). Downstaging was defined as post-NET decrease in category. We included 123 patients; the majority were cT2 (n = 59) or cT3 (n = 35), and cN0 (n = 81). Median age was 70.0 years (interquartile range 62.1-76.0). Forty-two patients (34.1%) were clinically node-positive. After NET, 73 (59.8%) underwent breast-conserving surgery. All patients underwent sentinel lymph node biopsy, and 12 (9.8%) underwent completion axillary lymph node dissection. In-breast downstaging was achieved in 51 (41.5%) patients, 1 (0.8%) had breast pCR, and 14 (11.4%) had breast upstaging. Axillary downstaging was achieved in 10 (23.8%), 6 patients (14.3%) had nodal pCR, and 14 (33.3%) had axillary upstaging. At 10-year follow-up, local recurrence was 1% and distant recurrence was 14%, while disease-free survival was 82%. After adjusting for demographic and clinical factors, age was the only characteristic associated with mortality (hazard ratio 1.07, 95% confidence interval 1.01-1.13). In HR+ BC treated with NET, long-term disease-free survival is good, although nodal pCR is uncommon for cN+ patients. Future studies are needed to elucidate optimal neoadjuvant systemic therapy and to delineate oncologically safe strategies to deescalate axillary management for residual microscopic disease.

Peritumoral edema enhances MRI-based deep learning radiomic model for axillary lymph node metastasis burden prediction in breast cancer

To investigate whether peritumoral edema (PE) could enhance deep learning radiomic (DLR) model in predicting axillary lymph node metastasis (ALNM) burden in breast cancer. Invasive breast cancer patients with preoperative MRI were retrospectively enrolled and categorized into low (< 2 lymph nodes involved (LNs+)) and high (≥ 2 LNs+) burden groups based on surgical pathology. PE was evaluated on T2WI, and intra- and peri-tumoral radiomic features were extracted from MRI-visible tumors in DCE-MRI. Deep learning models were developed for LN burden prediction in the training cohort and validated in an independent cohort. The incremental value of PE was evaluated through receiver operating characteristic (ROC) analysis, confirming the improvement in the area under the curve (AUC) using the Delong test. This was complemented by net reclassification improvement (NRI) and integrated discrimination improvement (IDI) metrics. The deep learning combined model, incorporating PE with selected radiomic features, demonstrated significantly higher AUC values compared to the MRI model and the DLR model in the training cohort (n = 177) (AUC: 0.953 vs. 0.849 and 0.867, p < 0.05) and the validation cohort (n = 111) (AUC: 0.963 vs. 0.883 and 0.882, p < 0.05). The complementary analysis demonstrated that PE significantly enhances the prediction performance of the DLR model (Categorical NRI: 0.551, p < 0.001; IDI = 0.343, p < 0.001). These findings were confirmed in the validation cohort (Categorical NRI: 0.539, p < 0.001; IDI = 0.387, p < 0.001). PE improved preoperative ALNM burden prediction of DLR model, facilitating personalized axillary management in breast cancer patients.

The surgical management of axillary lymph node disease in breast cancer patients

The precise assessment and management of the axillary lymph nodes in breast cancer is crucial for regional control, disease staging, selection of adjuvant chemotherapy strategies, and prediction of prognosis, with a general downward trend in surgical management. For early breast cancer with negative axillary lymph node metastases, sentinel lymph node biopsy (SLNB) has replaced axillary lymph node dissection (ALND) as the criterion for axillary status measurement. Patients can be exempted from ALND if they have negative SLNB results. However, it remains to be carefully decided in China whether patients with one or two positive nodes in SLNB can be spared from ALND. However, consensus has been met that patients who meet the criteria of the Z0011 study can be exempted from ALND. For breast cancer patients with positive axillary lymph nodes metastases at the beginning of treatment, the clearance of lymph node disease can be achieved by neoadjuvant therapy, with a reduced rate of complications related to ALND. In particular, there are still many debates associated with SLNB after neoadjuvant therapy, such as whether patients who remain axillary lymph node positive can be spared from ALND. Exploratory and validation studies related to the SLNB avoidance criteria are still controversial. In the future, clinicians should consider the characteristics of patients, the risk of recurrence, and adjuvant treatment regimens to develop individualized axillary lymph node management.

Axillary management and long-term oncologic outcomes in breast cancer patients with clinical N1 disease treated with neoadjuvant chemotherapy

BackgroundLow false negative rates can be achieved with sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) in breast cancer (BC) patients with clinical N1 (cN1) disease. We examined changes in axillary management and oncologic outcomes in BC patients with cN1 disease receiving NAC.MethodsBC patients with biopsy proven cN1 disease treated with NAC were selected from our institutional cancer registry (2014–2017). Patients were grouped by axillary management, axillary lymph node dissection (ALND), SLNB followed by ALND, or SLNB alone. Univariable and multivariable survival analysis for recurrence-free survival (RFS) and overall survival (OS) were performed.Results81 patients met inclusion criteria: 31 (38%) underwent ALND, 25 (31%) SLNB + ALND, and 25 (31%) SLNB alone. A SLN was identified in 45/50 (90%) patients who had SLNB. ALND was performed in 25/50 (50%) patients who had SLNB: 18 for a + SLNB, 5 failed SLNB, and 2 insufficient SLNs. 25 patients had SLNB alone, 17 were SLN- and 8 SLN+. In the SLNB alone group, 23/25 (92%) patients received adjuvant radiation (RT). 20 (25%) patients developed BC recurrence: 14 distant (70%), 3 local (15%), 2 regional + distant (10%), and 1 contralateral (5%). In the SLNB alone group, there was 1 axillary recurrence in a patient with a negative SLNB who did not receive RT. Univariable survival analysis showed significant differences in RFS and OS between axillary management groups, ALND/SLNB + ALND vs. SLNB alone (RFS: p = 0.006, OS: p = 0.021). On multivariable survival analysis, worse RFS and OS were observed in patients with TNBC (RFS: HR 3.77, 95% CI 1.70–11.90, p = 0.023; OS: HR 8.10, 95% CI 1.84–35.60, p = 0.006).ConclusionsSLNB alone and RT after NAC in BC patients with cN1 disease who have negative SLNs at surgery provides long-term regional disease control. This analysis provides support for the practice of axillary downstaging with NAC and SLNB alone.

ASO Author Reflections: Evolving Paradigms in Axillary Management for Breast Cancer: Insights from the ISPY-2 Neoadjuvant Chemotherapy Trial.

ASO Author Reflections: Evolving Paradigms in Axillary Management for Breast Cancer: Insights from the ISPY-2 Neoadjuvant Chemotherapy Trial.

227 Retrospective Study to Assess Axillary Management and Oncological Outcome After Neoadjuvant Chemotherapy for Patients with Breast Cancer

Abstract Aim Evaluation of the effect of neoadjuvant chemotherapy on axillary nodal status. The secondary objective was to evaluate the percentage of patients who are eligible for SLNB after neoadjuvant chemotherapy. Method This retrospective study was conducted by collecting data during the period from October 2019 to July 2021. The study included 64 patients who had biopsy-proven locally advanced breast cancer with clinically or radiologically positive axillary LNs, had been receiving neoadjuvant chemotherapy at the Clinical Oncology Department, and underwent surgery after neoadjuvant therapy at the surgical oncology unit of Alexandria Main University Hospital. Exclusion criteria were as follows: Patients with early-stage breast cancer, metastatic stage IV breast cancer, unfit/refusing neoadjuvant therapy, aged less than 18 years or more than 75 years or clinically and radiologically negative axilla. Data were collected retrospectively to assess the oncological and surgical outcomes after completing NAC. The files of 450 patients were reviewed, and only 64 patients were eligible patients to be included in our study. Results Complete pathological response (ypT0ypN0) was found in six of the 64 patients in our study. Four patients were triple-negative, and two patients were HER2-enriched biological subtype. One patient was T1, one patient was T2, one patient was T3, and three patients were T4. One patient was N1, four patients were N2, and one patient was N3. Conclusions Post-neoadjuvant ultrasound is essential for assessment of axillary response. Approximately 44.4% of patients with negative post-neoadjuvant axillary ultrasound can avoid unnecessary ALN clearance. Accurate axillary staging is the cornerstone for omission of axillary clearance after neoadjuvant among patients.

Tailored axillary surgery with or without axillary lymph node dissection followed by radiotherapy in patients with clinically node-positive breast cancer (OPBC-03/SAKK 23/16/IBCSG 57-18/ABCSG-53/GBG-101-TAXIS).

TPS611 Background: Axillary lymph node dissection (ALND) is standard of care for most patients with clinically node-positive breast cancer (cN+BC), either in the adjuvant setting or in case of residual nodal disease after neoadjuvant chemotherapy (NACT). At least one quarter of patients with breast cancer experience long term morbidity after ALND. The TAXIS trial was designed to investigate if axillary radiotherapy (ART) can replace ALND in patients with cN+ BC who underwent tailored axillary surgery (TAS), which is recognized as one of the most important uncertainties and controversies in axillary management of patients with breast cancer. Methods: To test the remaining indications for ALND in clinical practice, we designed the international, multicenter, phase-III, non-inferiority, randomized controlled TAXIS trial to be pragmatic (average PRECIS-2 score of 4.44). Accordingly, most study domains follow usual care conditions, including eligibility (following routine indications for ALND in clinical practice), surgical skills and techniques, and follow up. The radiation oncology protocol included detailed recommendations and an extensive quality assurance program, which was developed to address the limitations of prior landmark trials and increase acceptability among recruiters. The main objective of the trial is to demonstrate that treatment with TAS and ART is non-inferior to TAS and ALND in terms of disease-free survival (DFS) of patients with cN+ BC detected by imaging or palpation in the upfront surgery setting or in case of residual disease after NACT. Randomization at a 1:1 ratio is mainly performed intraoperatively to either use TAS followed by ALND and regional nodal irradiation excluding the dissected axilla as a target volume (arm A) or to use TAS followed by regional nodal irradiation including the full axilla (arm B). The sample size is based on the primary endpoint DFS. With a type I error of 5% and a power of 80%, 385 events will be needed to show non-inferiority of TAS and axillary RT in comparison to ALND with a non-inferiority hazard ratio of 1.289 (corresponding to a DFS at 5 years of 80% in the ALND arm and 75% in the TAS and axillary RT arm). The sample size was calculated to be 1500 patients (750 per arm). Enrolment started in July 2018 and will stop after reaching 1500 patients, which is expected to be completed by Q4/2025. With currently 51 active sites from Europe, Canada and Korea within the network of the Oncoplastic Breast Consortium (OPBC), &gt;950 patients were randomized by January 2024. Another 14 sites in Europe, USA, and South America will join the trial in 2024. The interim analysis (after 20% of the required events) is expected for Q4/2024 and will be reviewed by the IDMC. The primary endpoint analysis is planned in Q4/2030. Clinical trial information: NCT03513614 .

Breast Articles From 2023: Informing Practice Across the Continuum of Care.

With new investigations and clinical trials in breast oncology reported every year, it is critical that surgeons be aware of advances and insights into the evolving care paradigms and treatments available to their patients. This article highlights five publications found to be particularly impactful this past year. These articles report on efforts to select the minimal effective dose of tamoxifen for prevention, to challenge the existing age-based screening guidelines as they relate to race and ethnicity, to refine axillary management treatment standards, to optimize systemic therapy in multidisciplinary care settings, and to reduce the burden of breast cancer-related lymphedema after treatment. Taken together, these efforts have an impact on all facets of the continuum of care from prevention and screening through treatment and survivorship.

Current axillary management of patients with early breast cancer and low-volume nodal disease undergoing primary surgery: results of a United Kingdom national practice survey

PurposeUK NICE guidelines recommend axillary node clearance (ANC) should be performed in all patients with biopsy-proven node-positive breast cancer having primary surgery. There is, however, increasing evidence such extensive surgery may not always be necessary. Targeted axillary dissection (TAD) may be an effective alternative in patients with low-volume nodal disease who are clinically node negative (cN0) but have abnormal nodes detected radiologically. This survey aimed to explore current management of this group to inform feasibility of a future trial.MethodsAn online survey was developed to explore current UK management of patients with low-volume axillary disease and attitudes to a future trial. The survey was distributed via breast surgery professional associations and social media from September to November 2022. One survey was completed per unit and simple descriptive statistics used to summarise the results.Results51 UK breast units completed the survey of whom 78.5% (n = 40) reported performing ANC for all patients with biopsy-proven axillary nodal disease having primary surgery. Only 15.7% of units currently performed TAD either routinely (n = 6, 11.8%) or selectively (n = 2, 3.9%). There was significant uncertainty (83.7%, n = 36/43) about the optimal surgical management of these patients. Two-thirds (n = 27/42) of units felt an RCT comparing TAD and ANC would be feasible.ConclusionsANC remains standard of care for patients with low-volume node-positive breast cancer having primary surgery in the UK, but considerable uncertainty exists regarding optimal management of this group. This survey suggests an RCT comparing the outcomes of TAD and ANC may be feasible.

Abstract ED05-01: Demystifying the Axilla: Challenging scenarios in the upfront surgery setting and after NAC

Abstract Management of the axilla has evolved significantly over time, with a trend toward less extensive axillary surgery. While historically, all patients underwent axillary lymph node dissection (ALND) due to the Halstedian belief that ALND was essential for the cure of breast cancer, advances in systemic therapy, radiotherapy, and understanding of tumor biology have resulted in the abandonment of ALND for a large proportion of patients having upfront surgery with limited nodal disease, and in those with no residual nodal disease after neoadjuvant systemic therapy. Over time, axillary management has become increasingly complicated, with significant variability in real-world management for different clinical scenarios. In this talk, we will address challenging scenarios in axillary management, both in the upfront surgery setting and after neoadjuvant chemotherapy (NAC). In the upfront surgery setting, we will address management of a positive sentinel node in patients treated with mastectomy, management of ≥ 3 positive sentinel nodes after lumpectomy or mastectomy, and the use of sentinel lymph node biopsy for patients with clinically node-positive hormone receptor (HR) positive/human epidermal growth factor receptor 2 (HER2) negative breast cancer. In the setting of patients receiving NAC, we will discuss the optimal approach to the axilla in patients with residual disease after NAC, and in those with locally advanced breast cancer. As we move away from ALND in low-risk scenarios where data from randomized and prospective trials have demonstrated oncologic safety, we await results from ongoing clinical trials to provide us with high-level evidence regarding the safety of omission of ALND in high-risk patients with more extensive nodal disease. Citation Format: A. Barrio. Demystifying the Axilla: Challenging scenarios in the upfront surgery setting and after NAC [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr ED05-01.

Abstract PO5-23-01: SentiNeo: A feasibility study on a magnetic approach to targeted axillary dissection and sentinel lymph node biopsy after neoadjuvant chemotherapy

Abstract Background Neoadjuvant chemotherapy (NAC) is increasingly used to treat certain breast cancer subtypes, and often, with good axillary response. Axillary management after NAC has become a contentious topic. Low detection rates and high false negative rates for sentinel lymph node biopsies (SLNB) could be due to the chemotherapy-induced fibrosis and blockage of the lymphatic drainage. Complete axillary response raises the dilemma of whether axillary clearance is still necessary after NAC in node positive patients. Targeted axillary dissection (TAD) is a safe alternative but the optimal method for index metastatic lymph node marking and lymphatic mapping of additional SLNs is largely undetermined. In SentiNeo, we study the feasibility and accuracy of using superparamagnetic iron oxides nanoparticles (SPIO) and magnetic seeds for axillary staging after NAC. Methods: Patients from two hospitals undergoing NAC were included: 40 without (cN0) and 40 with (cN+) axillary metastases. For cN0, SPIO was injected before and Technetium (Tc99) after NAC. For cN+, a magnetic clip was inserted into the index metastatic node together with SPIO injection before and Tc99 after NAC. Endpoints were 1) Index node detection and 2) SLN detection and concordance rates. Detection rate was defined as the proportion of patients who had SLNs detected as per tracer (using both magnetometer and gamma probe). Concordance was defined as the number of nodes marked by both SPIO and Tc99, divided by the total number of Tc99 marked nodes. As this is a feasibility study, no calculations for statistical significance were done. Results: All 80 patients have been included and 60 have completed NAC and surgery: 35 cN0 with SLNB and 25 cN+ with TAD. Overall, SLN detection rates (excluding the index nodes) were 83.3% (50/60) for SPIO and 76.7% (46/60) for Tc99. In cN0, SLN detection rate was 85.7% (30/35) for SPIO) and 88.6% (31/35) for Tc99. In cN+, the index node was found in 24 of 25 patients. One patient did not receive a magnetic clip due to administrative error. The SLN detection rate (excluding index nodes) was 80% (20/25) for SPIO) and 60% (15/25) for Tc99. In total, 142 lymph nodes were retrieved, of which 71 contained both tracers. The concordance was 84% (out of 84 nodes detected with Tc99, 71 were also detected with SPIO). However, the reversed concordance was only 55% (out of 129 nodes detected with SPIO, 71 were radioactive). The overall mean (median) number of retrieved nodes were 2.2 (2) for SPIO and 1.4 (1) for Tc99. Conclusions: In this pilot study we have shown that injecting SPIO before NAC is feasible with detection rates comparable to Tc99injected after NAC. More nodes were retrieved with SPIO and furthermore, we hypothesize that these nodes might be more representative than nodes detected with a tracer injected after NAC. Finding the index node using the SentiMag probe was easy. For SLN detection with SPIO the same probe was used, making the magnetic approach to axillary staging an appealing alternative with no need for an extra localisation before surgery or access to nuclear medicine facilities. These findings justify a larger study which is in planning. Table. Citation Format: Kian Chin, Roger Olofsson Bagge, Nushin Mirzaei, Anikó Kovács, Henrik Leonhardt, Pontus Zaar, Andreas Karakatsanis, Eirini Pantiora, Staffan Eriksson, Maria Ekholm, Alastair Thompson, Peter Barry, Michael Boland, Vivian Man, Ava Kwong, Fredrik Wärnberg. SentiNeo: A feasibility study on a magnetic approach to targeted axillary dissection and sentinel lymph node biopsy after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-23-01.

Abstract PO2-23-04: Magnetic Seeds, used to Locate the Metastatic Axillary Lymph Node placed before Neoadjuvant Chemotherapy for Breast Cancer Treatment, do not interfere the pre-surgical MRI Breast response assessment

Abstract Background: Axillary management in clinically node-positive patients who converted to ycN0 after neoadjuvant chemotherapy (NAC) for breast cancer (BC) remains under research with the aim of de-escalation of axillary lymph node dissection (ALND). A magnetic seed is one of the several positive lymph nodes marking techniques used in targeted axillary dissection (TAD) for patients with cN1 breast cancer undergoing neoadjuvant systemic therapy. It has been criticized for its potential masking effect due to the artefact it produces in the MRI sequences used to assess a proper breast response. This study evaluates if the magnetic seeds placed before NAC for guided TAD have influenced in the breast MRI response assessments. Methods: From October 2021 to June 2023, patients with cT0-4 cN1 breast cancer who were candidates for primary systemic treatment were prospectively recruited. Once a breast lesion and axillary node positivity were confirmed, a based hydrogel marker and a magnetic seed, respectively, were placed prior NAC. Once systemic treatment was completed, imaging techniques were used to assess the response, with MRI being the imaging technique of choice to assess breast response and axillary ultrasound the imaging technique of choice to assess axillary response. Surgical pathological confirmation of response in the axilla was by TAD, including sentinel lymph node and magnetic clipped node resection. Results: A total of 43 patients were included and their characteristics are shown in Table 1. In 16 patients (37%) the tumour was located in the upper outer quadrant (UOQ). In this group, the susceptibility artefact produced by the magnetic seed in the MRI created a black hole obscuring the axilla with a mean diameter of 69 mm (range: 57-76 mm). In no case did the halo interfere with the correct MRI visualisation of the breast marker. By MRI, the mean distance of the artifact halo from the breast marker or residual breast lesion was 40 mm (range: 13-79 mm). Overall, complete radiological response (ycCR) was reported in 20 patients (46%), breast only in 21 (49%) and axilla only in 38 (88%) patients. In 5 patients, preoperative axillary ultrasound revealed residual axillary disease, confirmed by FNA, lead to direct ALND. In the remaining 38 patients the axillary TAD assessment was completed. In all cases, the magnetic clipped node was successfully surgically removed. Pathological complete response (pCR) was confirmed in 9 (21%), breast only in 11 (26%) and axilla only in 13 (30%) patients. MRI diagnostic performance in detecting residual breast disease after NAC was not altered by the magnetic clipped node artifact when comparing the tumour location in the UOQ to the other quadrants (AUC 0.764 vs. 0.702; p=0.698). Conclusions: Surgical axillary staging remains the most reliable method for assessing the axillary response after NAC. Target axillary dissection guided by magnetic seed placed before NAC is an effective and accurate technique. The artifact generated in the MRI does not interfere with the pre-surgical breast response assessment after neoadjuvant systemic treatment. Table 1: Patients and tumor characteristics Citation Format: Martin Espinosa-Bravo, Joaquin Rivero Deniz, Clara Morales Comas, Javier de la Torre Fernandez de Vega, Irene Vives Rosello, Enrica Esposito, Vicente Peg Camara, María De Les Neus Rus Calafell, Ignacio Miranda Gomez, Christian Siso Raber. Magnetic Seeds, used to Locate the Metastatic Axillary Lymph Node placed before Neoadjuvant Chemotherapy for Breast Cancer Treatment, do not interfere the pre-surgical MRI Breast response assessment [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-23-04.