Axillary Lymph Node Dissection Research Articles

Less is not more, but just as good. Omitting axillary lymph node dissection is possible with adequate adjuvant therapy

Less is not more, but just as good. Omitting axillary lymph node dissection is possible with adequate adjuvant therapy

Radar localization of breast and axillary lesions with SCOUT: a prospective single institution pilot study.

Wire-guided localization has been the mainstay of localization techniques for non-palpable breast and axillary lesions prior to excision. Evidence is still growing for relatively newer localization technologies. This study evaluated the efficacy of the wireless localization technology, SCOUT®, for both breast and axillary surgery. Data were extracted from a prospective database (2021-2023) of consecutive patients undergoing wide local excision, excisional biopsy, targeted axillary dissection, or axillary lymph node dissection with SCOUT at a high-volume tertiary centre. Rates of successful reflector placement, intraoperative lesion localization, and reflector retrieval were evaluated. A survey of surgeon-reported ease of lesion localization and reflector retrieval was also evaluated. ACTRN386751. One-hundred-ninety-five reflectors were deployed in 172 patients. Median interval between deployment and surgery was 3 days (range 1-20) and mean distance from reflector to lesion was 3.2 mm (standard deviation, SD 3.1). Rate of successful localization and reflector retrieval was 100% for both breast and axillary procedures. Mean operating time was 65.8 min (SD 33). None of the reflectors migrated. No reflector deployment or localization-related complications occurred. Ninety-eight percent of surgeons were satisfied with ease of localization for the first half of cases. SCOUT is an accurate and reliable method to localize and excise both breast and axillary lesions, and it may overcome some of the limitations of wire-guided localization.

Metaplastic breast cancer with a unique presentation and complete response to chemotherapy: a case report

BackgroundMetaplastic breast carcinomas are a rare variant group of breast carcinomas. They are usually high-grade and triple-negative tumors. They often present with large primary tumor sizes. However, the involvement of axillary lymph nodes is infrequent at the time of diagnosis. Metaplastic breast carcinomas are associated with a worse prognosis and a poorer response to chemotherapy in comparison with other non-metaplastic triple-negative breast cancers. Up until this point, there are no specific treatment recommendations for metaplastic breast carcinomas beyond those intended for invasive breast cancer in general.Case presentationA 40-year-old woman complained of a palpable mass in her left axilla. On ultrasonography, the mass was solid, spindle-shaped, hypoechoic with regular borders, and exhibited decreased vascularity. At first, the mass appeared to be of a muscular origin. There was not any clinical nor ultrasonic evidence of a primary breast tumor. On magnetic resonance imaging, the axillary mass was a well-defined with regular borders, measuring 24 × 35 mm. Needle biopsy showed a spindle cell tumor with mild to moderate atypia. The subsequent surgical resection revealed a spindle cell neoplasm within a lymph node, favoring a metastatic origin of the tumor. The tumor cells lacked expression of estrogen, progesterone, and HER2 receptors. PET-CT scan indicated pathological uptake in the left breast. Accordingly, the patient was diagnosed with metaplastic breast cancer that had metastasized to the axillary lymph node. She commenced a combined chemotherapy regimen of doxorubicin and cyclophosphamide. After six treatment cycles, she underwent left modified radical mastectomy with axillary lymph node dissection. Pathological examination of the specimens revealed a total burn-out tumor in the breast due to excellent treatment response. There were no residual tumor cells. All dissected lymph nodes were free of tumor. At the one-year follow-up, the patient showed no signs of tumor recurrence.ConclusionThis report sheds light on a distinctive presentation of metaplastic breast carcinoma, emphasizing the need for vigilance in diagnosing this rare and aggressive breast cancer variant. In addition, the patient’s remarkable response to chemotherapy highlights potential treatment avenues for metaplastic breast cancer.

Longitudinal ultrasound-based AI model predicts axillary lymph node response to neoadjuvant chemotherapy in breast cancer: a multicenter study.

Developing a deep learning radiomics model from longitudinal breast ultrasound and sonographer's axillary ultrasound diagnosis for predicting axillary lymph node (ALN) response to neoadjuvant chemotherapy (NAC) in breast cancer. Breast cancer patients undergoing NAC followed by surgery were recruited from three centers between November 2016 and December 2022. We collected ultrasound images for extracting tumor-derived radiomics and deep learning features, selecting quantitative features through various methods. Two machine learning models based on random forest were developed using pre-NAC and post-NAC features. A support vector machine integrated these data into a fusion model, evaluated via the area under the curve (AUC), decision curve analysis, and calibration curves. We compared the fusion model's performance against sonographer's diagnosis from pre-NAC and post-NAC axillary ultrasonography, referencing histological outcomes from sentinel lymph node biopsy or axillary lymph node dissection. In the validation cohort, the fusion model outperformed both pre-NAC (AUC: 0.899 vs. 0.786, p < 0.001) and post-NAC models (AUC: 0.899 vs. 0.853, p = 0.014), as well as the sonographer's diagnosis of ALN status on pre-NAC and post-NAC axillary ultrasonography (AUC: 0.899 vs. 0.719, p < 0.001). Decision curve analysis revealed patient benefits from the fusion model across threshold probabilities from 0.02 to 0.98. The model also enhanced sonographer's diagnostic ability, increasing accuracy from 71.9% to 79.2%. The deep learning radiomics model accurately predicted the ALN response to NAC in breast cancer. Furthermore, the model will assist sonographers to improve their diagnostic ability on ALN status before surgery. Our AI model based on pre- and post-neoadjuvant chemotherapy ultrasound can accurately predict axillary lymph node metastasis and assist sonographer's axillary diagnosis. Axillary lymph node metastasis status affects the choice of surgical treatment, and currently relies on subjective ultrasound. Our AI model outperformed sonographer's visual diagnosis on axillary ultrasound. Our deep learning radiomics model can improve sonographers' diagnosis and might assist in surgical decision-making.

Evaluating the role of level 3 axillary lymph node dissection in metastatic melanoma: Can we predict involvement?

MSLT-2 and DECOG-SLT established that immediate complete axillary lymph node dissection (CLND) did not correlate with an increase in melanoma-specific survival when compared with active ultrasound observation in patients with sentinel lymph node(SLN)-positivedisease. After those trials, there was a shift towardperforming CLND only for clinically node-positive disease. With these changes, we sought to determine the role of level III axillary lymph nodes in bulky disease and how the use of neoadjuvant therapy may impact the rate of positivity in level III axillary nodes. We performed a retrospective chart review on all patients who underwent axillary CLND for cutaneous melanoma by one surgeon at an academic center from 2014 to 2022. These patients underwent CLND based on either having SLN+ disease or having clinically palpable or radiographically bulky disease. Of 95 patients included, there were 7 (7.3%) patients with level III positivity. One was SLN+ (1.0%), while 3 (3.1%) had bulky disease and neoadjuvant therapy, and 3 (3.1%) had bulky disease without neoadjuvant therapy. No preoperative factors were identified that predicted level III involvement. After performing CLND, the patients who had clinically palpable or radiographically bulky disease and neoadjuvant therapy had higher percent necrosis of nodes in levels I and II but not III.At 5 years, overall survival and recurrence-free survival were improved in those without level III involvement (58%and 64%, respectively) when compared to those with level III involvement (41% and50%), though this was not statistically significant. Further study may identify better prognostic factors for level III positivity, allowing for the possibility of dissecting only levels I and II or even replacing CLND with targeted node dissections.

Factors Associated With Additional Axillary Disease in Patients With Positive Sentinel Lymph Nodes After Neoadjuvant Chemotherapy for Breast Cancer.

Background: In previous studies, breast cancer patients with positive sentinel lymph node(s) (SLN) after neoadjuvant chemotherapy (NAC) frequently had additional nonSLN involvement. Per guidelines, residual SLN disease warrants completion axillary lymph node dissection (cALND), which has increased morbidity. Given recent improvements in NAC, we hypothesized that nonSLN positivity may be lower than previously reported for certain subgroups.Methods: We retrospectively reviewed breast cancer patients who received NAC and had positive lymph nodes on SLN biopsy or targeted axillary dissection and underwent cALND at one institution in 1/2018-8/2023. Associations between nonSLN positivity and clinicopathologic factors were assessed with Fisher's exact test and multivariable logistic regression.Results: There were 122 female patients. Median age was 48years. Initially, 15 patients (12.3%) were cN0 and 107 patients (87.7%) were cN1. Largest SLN deposit was macrometastasis in 96 patients (78.7%), micrometastasis in 23 patients (18.9%), and isolated tumor cells in 3 patients (2.5%). Overall, 53 patients (43.4%) had nonSLN involvement. NonSLN positivity was higher in patients with cN1, ER+ HER2-, ypT2-3, SLN macrometastasis, and multiple positive SLN. On multivariable analysis, cN1 and ER+ HER2- remained associated with nonSLN positivity.Discussion: Among patients with positive SLN after NAC, clinically node positive and ER+ HER2- patients were more likely to have nonSLN involvement. Our findings support guidelines to consider omitting cALND in clinically node negative patients. With improving NAC, optimal axillary sampling, and radiation, omitting cALND may be safe in some clinically node positive triple negative or HER2+ patients with low volume residual disease, but further research is needed.

Oncologic Outcomes for Different Axillary Staging Techniques in Patients with Nodal-Positive Breast Cancer Undergoing Neoadjuvant Systematic Treatment: A Cancer Registry Study.

Targeted approaches such as targeted axillary dissection (TAD) or sentinel lymph node biopsy (SLNB) showed false-negative rates of < 10% compared with axillary lymph node dissection (ALND) in patients with nodal-positive breast cancer undergoing neoadjuvant systemic treatment (NAST). We aimed to evaluate real-world oncologic outcomes for different axillary staging techniques. We identified nodal-positive breast cancer patients undergoing NAST from 2016 to 2021 from the state cancer registry of Baden-Wuerttemberg, Germany. Invasive disease-free survival (iDFS) was assessed using Kaplan-Meier statistics and multivariate Cox regression models (adjusted for age, ypN stage, ypT stage, and tumor biologic subtype). A total of 2698 patients with a median follow-up of 24.7 months were identified: 2204 underwent ALND, 460 underwent SLNB (255 with ≥ 3 sentinel lymph nodes [SLNs] removed, 205 with 1-2 SLNs removed), and 34 underwent TAD. iDFS 3 years after surgery was 69.7% (ALND), 76.6% (SLNB with ≥ 3 SLNs removed), 76.7% (SLNB with < 3 SLNs removed), and 78.7% (TAD). Multivariate Cox regression analysis showed no significant influence of different axillary staging techniques on iDFS (hazard ratio [HR] for SLNB with < 3 SLNs removed 0.96, 95% confidence interval [CI] 0.62-1.50; HR for SLNB with ≥ 3 SLNs removed 0.86, 95% CI 0.56-1.3; HR for TAD 0.23, 95% CI 0.03-1.64; ALND reference), and for ypN+ (HR 1.92, 95% CI 1.49-2.49), triple-negative breast cancer (HR 2.35, 95% CI 1.80-3.06), and ypT3-4 (HR 2.93, 95% CI 2.02-4.24). These real-world data provide evidence that patient selection for de-escalated axillary surgery for patients with nodal-positive breast cancer undergoing NAST was successfully adopted and no early alarm signals of iDFS detriment were detected.

Residual Axillary Metastases in Node-Positive Breast Cancer Patients After Neoadjuvant Treatment: A Register-Based Study.

Lymph node (LN) metastasis after neoadjuvant chemotherapy (NACT) generally warrants axillary lymph node dissection, which opposes guidelines of upfront surgery in many cases. We investigated the risk of having additional metastases in the axilla when the LNs removed by targeted axillary dissection (TAD) harbored metastases after NACT. We aimed to identify subgroups suitable for de-escalated axillary treatment. This register-based study used data from the Danish Breast Cancer Cooperative Group database. Data were analyzed with logistic regression models. The primary outcome was the metastatic burden in non-TAD LNs in patients with positive TAD LNs after NACT. Among 383 patients, < 66.6% positive TAD LNs (adjusted odds ratio [OR] 0.34, 95% confidence interval [CI] 0.17-0.62), only isolated tumor cells (ITCs) [OR 0.11, 95% CI < 0.01-0.82], and breast pathological complete response (pCR) [OR 0.07, 95% CI < 0.01-0.56] were associated with a low risk of having more than three positive non-TAD LNs. In 315 patients with fewer than three positive non-TAD LNs, the proportion of positive TAD LNs (OR 0.45, 95% CI 0.27-0.76 for 33.3-66.6% vs. > 66.6%), size of the TAD LN metastasis (OR 0.14, 95% CI 0.04-0.54 for ITC vs. macrometastasis), tumor size at diagnosis (OR 0.30, 95% CI 0.15-0.64 for 20-49mm vs. ≥ 50mm) and breast pCR (OR 0.38, 95% CI 0.15-0.96) were associated with residual LN metastases in the axilla. Breast pCR or ITC only in TAD LNs can, with reasonable certainty, preclude more than three positive non-TAD LNs. Additionally, patients with only ITCs in the TAD LN had a low risk of having any non-TAD LN metastases after NACT. De-escalated axillary treatment may be considered in both subgroups.

Abstract PO3-06-02: Ten years axillary recurrence and survival after omission of axillary lymph node dissection in breast cancer patients with micrometastases or isolated tumor cells in the sentinel node: A Danish national register study

Abstract Background: Until 2012, breast cancer patients with micrometastases (pN1mi) or isolated tumor cells (pN0(i)) in the sentinel node (SN) received axillary lymph node dissection (ALND). ALND is associated with lymphedema, paresthesia, functional impairment, and pain. In 2012, national Danish guidelines for patients with pN1mi and pN0(i) were changed reflecting several randomized clinical trials showing non-inferior prognosis when ALND was omitted. Since 2012, appr. 450 Danish breast cancer patients have been spared ALND each year. Development of axillary recurrence(AR) from minimal metastatic disease left in the axilla may take longer than experienced after macrometastatic disease. Hence, long-term follow-up is needed to evaluate the safety of omitting ALND for patients with pN1mi and pN0(i). Therefore, we aimed to investigate these outcomes with 10 years of follow-up. Methods: In this national register-based study, we included all women with primary breast cancer surgery between 01.01.2008 and 31.12.2021, who had pN1mi and pN0(i) in the SN. Women treated between 01.01.2008-31.12.2011 had received ALND, while in women treated between 01.01.2012 and 31.12.202,1 ALND was omitted. The two groups were compared with SN-negative patients (pN0) without ALND. The primary outcome was AR, and the secondary outcome was overall survival (OS). Information on surgery, nodal status, and recurrence were retrieved from the national Danish breast cancer group (DBCG) database. The definitions of pN1mi, pN0(i) and pN0 were according to AJCC, 8TH edition. We analyzed patient- and tumor characteristics with descriptive statistics, χ2 and Fisher exact test. The cumulative incidence of AR was calculated. OS was estimated using the Kaplan-Meier method and compared with a log-rank test. The effect of ALND was estimated with a Cox proportional hazards model, adjusting for age at operation, histology, malignancy grade, hormone receptor, HER2 status, and whether they received adjuvant systemic treatment or radiation therapy. With all statistical analysis, a two-tailed α-level of 0.05 was used. Results: 22,790 patients were included in the study. Overall,14.3% had pN1mi, 8.6% had pN0(i) and 77.1% had pN0. Of pN1mi or pN0(i) patients, 1490 had an ALND; 1227 patients with pN1mi and 263 patients with pN0(i). In 3737 patients ALND was omitted: 2036 with pN1mi and 1701 with pN0(i). Regarding the primary outcome, 1.1% of patients with pN1mi or pN0(i) had an AR, while 0.5% of the pN0 patients had AR. Analyzing patients with pN1mi or pN0(i) with or without ALND, 0.2% and 1.5%, respectively, had an AR. In subanalysis of patients with pN1mi with or without ALND, 0.2% and 1.8%, respectively, had an AR. In a subanalysis of patients with pN0(i), no patients with pN0(i) and ALND had an AR, while 1.1% of patients with pN0(i) had an AR when ALND was omitted. OS after 10 years of follow-up for the group of patients with pN1mi or pN0(i) was 81.5%; 83.7% for patients with and 79.12% for patients without ALND. For pN0 patients without ALND OS was 82%. This difference between the three groups was statistically significant(p&amp;lt; 0,01). However, when adjusting for risk factors, there was no statistically significant difference in OS between the patients with pN1mi or pN0(i) with and without ALND (p=0.6). Likewise, no statistically significant difference was found in OS, when looking at the subgroups of pN1mi with or without ALND (p=0.5) and pN0(i) with and without ALND(p=0.41). Conclusion: In this large register-based nationwide study we found a slightly higher rate of AR after 10 years of follow-up in breast cancer patients with micrometastases or isolated tumor cells in the SN if ALND was omitted. However, the axillary recurrence rate was low (&amp;lt; 2%), and after adjusting for other risk factors the increased recurrence rate did not affect OS. These results confirm the safety of omitting ALND in these patients. Citation Format: Riazan Hawaz-ali, Frederikke Munck, Tove Tvedskov, Niels Kroman. Ten years axillary recurrence and survival after omission of axillary lymph node dissection in breast cancer patients with micrometastases or isolated tumor cells in the sentinel node: A Danish national register study [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 PO3-06-02.

Abstract GS02-02: Are nodal ITCs after neoadjuvant chemotherapy an indication for axillary dissection? The OPBC05/EUBREAST-14R/ICARO study

Abstract Background: In patients with micro- and macrometastases in the sentinel lymph node (SLN) after neoadjuvant chemotherapy (NAC), additional positive nodes are found in &amp;gt;60% of cases and axillary lymph node dissection (ALND) is currently considered standard of care. The likelihood of finding additional positive lymph nodes in patients with residual isolated tumor cells (ITCs) is unknown, and the benefit of ALND is unclear. As a consequence, surgical management of the axilla in these patients is not standardized. We sought to evaluate how often additional positive lymph nodes are found, to determine factors associated with ALND, and to compare oncological outcomes in patients treated with and without ALND after identification of residual ITCs in the SLN. Methods: Data were collected from 42 centers: 20 in the Oncoplastic Breast Consortium (OPBC) and EUBREAST networks, and 22 in North and South America. We included patients with cT1-4 N0-3 breast cancer at diagnosis who underwent NAC followed by axillary staging with either SLN biopsy (SLNB) or targeted axillary dissection (TAD) and were found to have residual ITCs [ypN0(i+)]. Single-tracer mapping was allowed for cN0 patients, while dual mapping or TAD was required for cN+ cases. Axillary treatment included completion ALND and/or nodal radiotherapy (RT). Competing risk analysis was performed to assess the cumulative incidence rates of any axillary recurrence (AR), locoregional recurrence (LRR), and any invasive (locoregional or distant) recurrence. Five-year cumulative incidence rates were compared between patients who underwent ALND and those who did not using the Gray’s test. Type I error rate was set to 0.05 (α). Results: We included 412 patients treated with NAC followed by surgery from 01/2009-05/2022. 146 (35.4%) had completion ALND and 266 (64.6%%) did not. Median patient age was 48 years. The majority (57%) of patients had clinical T2 tumors, and 68% had biopsy-proven N1 disease. Most were HR+/HER2- (41%) or HER2+ (39%). Most patients (80%) received anthracycline and taxane-based chemotherapy regimens. Nodal RT was administered to 83% of patients. The median number of SLNs with ITCs was 1. Patients treated with ALND were more likely to have ITCs detected on frozen section (61% v 6.7%, p&amp;lt; 0.001), to have N2/3 disease at presentation (15.1% v 5.6%, p=0.001) and to have LVI (40% v 26%, p=0.004) (Table 1). There was no significant trend over time in the proportion of patients undergoing completion ALND during the study period (p=0.5). In the ALND group, additional positive nodes were found in 43/146 (29.5%) of cases, and consisted of macrometastases in 11/146 (7.5%), micrometastases in 9/146 (6.2%), and ITCs in 23/146 (15.8%). 5-year rates of any AR, LRR, and any invasive recurrence in the entire cohort were 2.7% (95% CI 1.2-5.4), 2.8% (95% CI 1.2-5.4) and 16% (95% CI 11-21), respectively. There was no statistical difference between patients who underwent ALND and those who did not in any of the 3 endpoints (2.2% v 3.1%, p=0.6), (2.6% v 3.0%, p=0.4) and (14% v 18%, p=0.12), respectively. Conclusion: The likelihood of finding additional positive lymph nodes in patients with ITCs after NAC is lower than in patients with residual micro- and macrometastases, and in the majority of cases, they contain ITCs. Nodal recurrence after omission of ALND is rare in this population. Overall, these results do not support routine ALND in patients with residual ITCs. Table 1. Clinicopathological Features of the Study Cohort, Stratified by Type of Axillary Surgery Frequency (row percent) reported for categorical variables, and median (IQR) reported for continuous variables. SLNB sentinel lymph node biopsy; TAD targeted axillary dissection; SLNs sentinel lymph nodes; LNs lymph nodes; pCR pathologic complete response; ACT anthracycline and taxane; AC anthracycline; H Herceptin, HP, Herceptin and Perjeta; TC taxol (or Taxotere) and carboplatinum; LVI lymphovascular invasion; BCS breast-conserving surgery. ^ Applied to HER2- tumors only (n=252). ^^ Applies to HER2+ tumors only (n=160). # LVI was present on core biopsy or final pathology. * Applies to BCS patients only (n=175). ** Applies to mastectomy patients only (n=237). Citation Format: Giacomo Montagna, Alison Laws, Massimo Ferrucci, Mary Mrdutt, Natália Polidorio, Varadan Sevilimedu, Tracy-Ann Moo, Andrea Barrio, Marissa K. Boyle, Flavia Vidal Cabero, Daniela Cocco, Fabio Corsi, Angelena Crown, Meghan R. Flanagan, Mehmet Ali Gulcelik, Callie Hlavin, Justyna Jelinska, Hasan Karanlik, Susan Kesmodel, Henry Kuerer, Sherko Küemmel, Cornelia Leo, Tehillah Menes, Melissa Pilewskie, Nina Pislar, Nicola Rocco, Jai Min Ryu, Leonardo Soares, Christoph Tausch, M. Umit Ugurlu, CICERO URBAN, Astrid Botty van de Bruele, Denise Vorburger, Fredrik Wärnberg, Anna Weiss, Austin Williams, Stephanie Wong, Steven G. Woodward, Susie X. Sun, Jennifer Q. Zhang, M. Firdos Ziauddin, Guldeniz Karadeniz Cakmak, Nuran Bese, Thorsten Kühn, Judy Boughey, Tari King, Nina Ditsch, Maggie Banys-Paluchowski, Monica Morrow, Walter Weber. Are nodal ITCs after neoadjuvant chemotherapy an indication for axillary dissection? The OPBC05/EUBREAST-14R/ICARO study [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 GS02-02.

Abstract PS01-04: To dissect or not to dissect? The surgeon’s perspective on the prediction of ≥ 4 axillary lymph node metastasis in cN0 T1-2 breast cancer: A comparative analysis of the per-protocol population of the SINODAR-ONE clinical trial

Abstract Objectives The role of axillary surgery in the management of breast cancer (BC) has evolved considerably over the past decades, with only a few routine indications for axillary lymph node dissection (ALND) remaining in clinical practice. However, de-escalation of axillary surgery, especially in BC patients with 1-3 positive sentinel lymph nodes (SLNs) challenges the recently established criteria for adjuvant treatment (i.e., combination therapy with abemaciclib, endocrine therapy, and chemotherapy in patients with ≥ 4 positive nodes). The question remains as to whether these patients should undergo further ALND to determine whether ≥ 4 nodes are positive. To further investigate the latest controversies in axillary management of BC patients and predict the presence of ≥ 4 axillary lymph node metastasis, we evaluated and compared patients ≥ 4 positive nodes in the per-protocol population of the SINODAR-ONE clinical trial. Patients in the standard arm (ALND) of the per-protocol population were evaluated, and a comparison of characteristics between patients with ≥ 4 metastatic lymph nodes versus patients with 1-3 metastatic lymph nodes was performed. Categorical variables were compared using the chi-square test or Fisher’s exact test, as appropriate. Multivariable analysis was performed using a logistic regression model to identify independent predictors of ≥4 axillary lymph node metastasis. Results: Overall, 403 cN0 T1-2 BC patients in the per-protocol population were randomized to receive ALND. Of these, 65 and 338 patients presented with ≥ 4 or 1-3 axillary lymph node metastasis, respectively. Invasive lobular BC (26.2% versus 14.5% if other histology, odds ratio (OR)=4.185, 95% confidence interval (95%CI)= 1.284-1.443, p= 0.041), G3 (38.5% versus 21.3% if G1-2, OR=5.930, 95%CI= 2.134-2.289, p= 0.015), pT2 (46.2% versus 30.5% if pT1, OR=5.260, 95%CI= 15.330-16.346, p= 0.022), and 2 positive SLNs (32.3% versus 13.6% if 1 positive SLN, OR=13.188, 95%CI= 1.179-1.280, p&amp;lt; 0.0001) were found to significantly increase the probability to present ≥4 axillary lymph node metastasis at definitive histopathological evaluation. Conclusions: The introduction of abemaciclib and other combination therapies has the potential to impact the surgical management of the axilla. Our results suggest that a minority of cN0 T1-2 BC patients may be understaged if ALND is not performed. However, the improvements and increasing effectiveness of combination therapies may sufficiently control and treat the axillary tumor-burden left behind, potentially reducing the need for extensive axillary surgery, as demonstrated by the promising 3-year oncological outcomes of the SINODAR-ONE trial. Although ALND may still be considered, after multidisciplinary team discussion, in individual patients presenting with specific risk factors for additional axillary disease (lobular, G3, pT2 BC with 2 positive SLNs), our suggestion is that routine ALND is not indicated for systemic therapy decision-making in the upfront surgical setting. Citation Format: Damiano Gentile, Wolfgang Gatzemeier, Andrea Sagona, Erika Barbieri, Alberto Bottini, Alberto Testori, Valentina Errico, Simone Di Maria Grimaldi, Giulia Caraceni, Shadya Darwish, Giuseppe Canavese, Corrado Tinterri. To dissect or not to dissect? The surgeon’s perspective on the prediction of ≥ 4 axillary lymph node metastasis in cN0 T1-2 breast cancer: A comparative analysis of the per-protocol population of the SINODAR-ONE clinical trial [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 PS01-04.

Abstract PO4-20-05: An open label phase III randomized trial to evaluate the efficacy of Post-chemotherapy Axillary Conservation Surgery in breast cancer (PACS)

Abstract Background- Axillary lymph nodes (ALN) status is the most important prognostic factor in breast cancer. Traditionally, a complete axillary lymph node dissection (ALND) has been standard of care for those patients who have a positive node pre-chemotherapy. However, lately axillary conservation is paving its way in the post-chemotherapy setting as well to avoid significant morbidity of ALND. Most sentinel node biopsy studies have failed to achieve the desired false negative rate(FNR). (Boughey JC et al, JAMA. 2013 Oct; Kuehn T et al, Lancet Oncol. 2013; Boileau JF et al, J Clin Oncol. 2015 Jan).We previously reported a low FNR of low axillary sampling (LAS) in the post-chemotherapy setting. (Parmar et al, JCO-GO, 2021) We are conducting a phase III, randomised controlled trial of LAS versus complete ALND in post-chemotherapy negative (ypN0) axilla. Aims and objectives- The primary objective is to assess the non-inferiority of LAS in patients who are rendered ypN0 by pre-operative chemotherapy with disease-free survival as primary end point. The secondary objectives are comparing the morbidity of ALND (lymphedema, paraesthesia, and shoulder dysfunction) in the LAS and ALND arms, and to evaluate the impact on overall survival, local, regional, and distant recurrence free survival and quality of life. Trial design- This is a prospective, open label, randomised, phase III trial where histologically proven, non-metastatic, cT1-4,N0-2 breast cancer patients who are rendered ycN0 after pre-operative systemic chemotherapy are being accrued. Patients with prechemo N3 disease, inflammatory breast cancer, recurrent disease, pregnancy associated breast cancer are being excluded from the study. The chemotherapy regimens and surgical assessment is as per standard institutional protocols. After obtaining informed consent, patients undergo LAS during surgery and lymph nodes(LN) are sent for frozen section analysis. If any LN is found to be involved, a complete ALND is carried out. If the staging procedure is negative, then patients are randomised into 2 groups- observation v/s complete ALND. Stratification factors are T stage, N stage, Hormone receptor status, Her2 receptor status and number of chemotherapy cycles taken. Morbidity assessment is done with- Constans shoulder score, arm volumetry, paraesthesia assessment, and a QOL questionnaire- Self-reported Breast cancer Lymphedema Symptom Experience Index (BCLSEI). A baseline assessment pre-surgery is followed by 6 monthly morbidity assessments and regular oncologically relevant follow-up up to 5 years. A two-sided log-rank test with an overall sample size of 2316 with a 10% dropout rate (1158 in ALND and 1158 in LAS group) achieves 80% power at a 0.05 significance level to detect a hazard ratio of 1.16 (upper limit of non-inferiority) when the proportion surviving in the control group is 0.71. An interim analysis will be carried out at 25% events and conditional power will be calculated. If the conditional power is below 20%, then the study will be discontinued for futility. The study has been approved by Institutional Ethics Committee (CTRI/2022/07/044461) Expected Study and Results- We started accrual in February 2023 and have screened 63 and randomized 45 patients until now. Ours is a first large randomised prospective study in the post-chemotherapy axillary management setting which will help us understand the efficacy of axillary conservation surgery in patients who are node negative post neoadjuvant chemotherapy. In future, lesser morbid procedures than LAS like targeted axillary dissection can be tested in the same trial. However, LAS as a technique of axillary conservation suits resource constraints and high volume setting such as ours. Citation Format: Shalaka Joshi, Jessicka Shah, Pallavi Daphale, Rohini Hawaldar, Anuradha Daptardar, Ayushi Sahay, Tanuja Shet, Palak Popat, Tabassum Wadasadawala, Nita Nair, Vani Parmar, Bipin Bandre, Shabina Siddique, Vaibhav Vanmali, Sudeep Gupta, Rajendra Badwe. An open label phase III randomized trial to evaluate the efficacy of Post-chemotherapy Axillary Conservation Surgery in breast cancer (PACS) [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 PO4-20-05.

Abstract PO4-19-07: Tailored Axillary Surgery (TAS) in Patients with Clinically Node-Positive Breast Cancer in the Upfront Surgery Setting: A Prospective, Single-Arm, Multicenter Trial

Abstract A brief background discussion: Axillary lymph node dissection (ALND), which can induce lymphedema, has been omitted in clinically node-negative(cN0) patients with positive sentinel lymph nodes (SLNs) if they meet the eligibility criteria of ACOSOG Z0011. Furthermore, the omission of ALND has been attempted through targeted axillary dissection (TAD) in patients whose clinically node-positive(cN+) status converts to ycN0 after neoadjuvant chemotherapy. However, ALND remains the standard of care in patients with cN+ who undergo upfront surgery. Trial design: This is a prospective, single-arm, multicenter phase II feasibility trial with the participation of 41 hospitals belonging to the breast cancer study group of Japan Clinical Oncology Group (JCOG). Tailored axillary surgery (TAS) removes labeled lymph node (LN) with clip, wire, or tattoo, palpable LNs, and SLNs. ALND is performed after TAS. These LNs removed by ALND other than TAS are defined as non-TAS LNs. Eligibility criteria: The eligibility criteria are as follows: 1) histologically-proven invasive breast cancer, 2) upfront surgery is planned, 3) pathologically diagnosed metastatic LN (cytology or core needle biopsy), 4) 1-3 LN metastases in level I by imaging, 5) cT1-3, and 6) females aged ≥18 and ≤74 years on the enrollment date. Specific aims: This trial aims to establish a surgical method of tailored axillary surgery (TAS) among patients with cN+ who undergo upfront surgery and to determine the appropriate criteria for the next phase III TAS trial, which omits ALND by TAS safely. The primary endpoint is the non-TAS LNs positive rate. Clinicopathological factors (the number of suspected metastases by imaging, the number of metastases in LNs resected by TAS, tumor size, and invasive ductal/lobular carcinoma) are analyzed to predict the non-TAS LN metastasis rate (e.g., &amp;lt; 10%). The secondary endpoints are the TAS LNs identification rate, marked LN resection rate, arm edema incidence rate, and QOL (FACT-B, QuickDASH). Statistical methods: In this trial, among the combinations of factors involved in treatment selection, the objective is to narrow down the combinations that will result in a non-TAS metastasis-positive rate of less than 10% when TAS is performed. For a single combination, 167 cases need to be considered to reject a non-TAS metastasis-positive rate of 10% or more (5% one-sided alpha error, 70% power, and 5% expected value). However, performing these studies for all combinations lacks feasibility. Therefore, we decided to improve the estimation accuracy by using a regression model with the non-TAS metastasis-positive rate as the outcome variable and the factors involved in treatment selection as explanatory variables and to search for combinations of factors with a non-TAS metastasis-positive rate less than 10%. Based on the rule of thumb that a sample size of at least ten times the number of factors is required when using regression methods, a regression model is used when 60 cases are accumulated. The combinations with a 90% confidence upper limit of less than 10% of non-TAS metastasis positivity as the predictive value of the regression model will be selected as candidate combinations that fulfill the conditions. If the accuracy of the predictive value is considered insufficient, 60 cases will be added sequentially up to a maximum of 300 cases. Present accrual and target accrual: The patient recruitment was started in April 2023. Up to 300 patients will be enrolled over a 2-year recruitment period. Twenty-one patients were already enrolled until July 2023. Citation Format: Kaori Terata, Yasuaki Sagara, Tadahiko Shien, Takehiko Sakai, Shin Takayama, Dai Kitagawa, Tsuguo Iwatani, Takahiro Tsukioki, Mami Ogita, Naoko Sanuki, Masayuki Yoshida, Hitoshi Tsuda, Seiichiro Yamamoto, Hiroji Iwata. Tailored Axillary Surgery (TAS) in Patients with Clinically Node-Positive Breast Cancer in the Upfront Surgery Setting: A Prospective, Single-Arm, Multicenter Trial [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 PO4-19-07.

Abstract PO4-22-08: Ten-Year Oncologic Outcomes in T1-3N1 Breast Cancer After Targeted Axillary Sampling: A Retrospective Study

Abstract Background Targeted axillary sampling (TAS) is a new surgical concept for the assessment of axillary lymph node status in breast cancer that is hypothesized to be more effective at minimizing postoperative morbidities than axillary lymph node dissection (ALND), provided the metastatic axillary lymph node can be accurately detected without missing data; however, the oncologic outcomes over long-term follow-up have not been sufficiently investigated. This was a retrospective analysis to evaluate the 10-year oncologic outcomes in T1-3N1 breast cancer after TAS. Methods Clinically, we defined TAS as removal of a bunch of ALNs located around SLNs and targeted LNs, but without full exposure of the axillary vein, long thoracic nerve and thoracodorsal nerve. Between 2008 and 2013, 230 female patients with cT1-3N1 breast cancer underwent breast and axillary surgery (ALND, n = 171; TAS, n = 59) at our institute. After TAS was applied, additional axillary radiotherapy was performed. Various postoperative complications, including postoperative seroma, lymphedema, and 10-year oncological outcomes, were evaluated and compared between the ALND and TAS groups. Results Although overall survival during the 10-year follow-up period was better in the TAS group, there was no statistically significant difference in oncologic outcomes, including locoregional recurrence, distant metastasis, and overall survival (p = 0.395, 0.818, and 0.555, respectively). Furthermore, the incidence of lymphedema on the ipsilateral arm was significantly higher in the ALND group (p &amp;lt; 0.001). Conclusions The 10-year oncological outcomes of TAS were not inferior to those of conventional ALND in T1-3N1 breast cancers; however, the incidence of lymphedema was significantly higher in the ALND group. Citation Format: Byeongju Kang, Jeeyeon Lee, Yee Soo Chae, Ho Yong PARK, Jin Hyang Jung. Ten-Year Oncologic Outcomes in T1-3N1 Breast Cancer After Targeted Axillary Sampling: A Retrospective Study [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 PO4-22-08.

Abstract PO3-22-09: Implementation of nanoparticle-assisted axillary staging: reduced axillary intervention for patients with node-positive breast cancer following neoadjuvant therapy

Abstract Background: Nanoparticle-assisted axillary staging (NAAS), which combines carbon nanoparticles with standard dual-tracer (radioisotope and blue dye) sentinel lymph node biopsy (SLNB), has shown excellent results in patients undergoing neoadjuvant therapy (NAC) for pre-NAC node-positive breast cancer. This pilot study aimed to explore the possible expansion of indications (pre-NAC cN2, and cN3 stages; ycN+ stage) for NAAS, which was the first attempt till now for patients undergoing NAC, and to select specific post-NAC individuals who might be exempt from axillary lymph node dissection (ALND), especially those with relatively low tumor burdens, such as ITCs and micrometastases. Method: The medical records of all consecutive patients with breast cancer were prospectively collected from the Breast Center, West China Hospital. Patients with invasive, pre-NAC node-positive breast cancer who underwent NAAS followed by ALND between April 2021 and February 2023 were included. The detection rate (DR), average number of sentinel or NAAS nodes, false negative rate (FNR), negative predictive value (NPV), and NAAS accuracy were assessed. Subgroup analyses according to different pre- and post-NAC cN stages, especially the pre-NAC cN2-3 stages and the post-NAC cN+ stages, which were not the focus of previous studies, were conducted using crosstabs. To screen possible patients who might exempt ALND, we focus on relationships between the status of axillary lymph nodes and the number or tumor burden of NAAS nodes. Results: A total of 241 eligible patients were included in the study. There were 153 (63.49%), 40 (16.60%), and 48 (19.92%) patients in pre-NAC cN1, cN2, and cN3 stages, respectively. The post-NAC stages of patients were not restricted, 38.17% (92/241) of them converted to ycN0 stages, while 61.83% (149/241) were still in ycN+ stages. A total of 232 (96.27%) eligible patients successfully underwent NAAS; the DR, NPV, accuracy, and FNR of NAAS were 96.27%, 95.97%, 97.84%, and 4.42%, respectively. Additionally, NAAS showed accuracies of 97.30% and 93.02% and FNRs of 7.14% and 9.09% in patients with pre-NAC cN2 and cN3 breast cancers, respectively. There was no statistical difference among the FNRs of NAAS in the pre-NAC cN1, cN2, and cN3 stages (p=0.134). Moreover, NAAS yielded FNRs of 0.00% in the ycN0 population and 6.02% in the ycN+ population, respectively (p=0.323). Accuracies reached 100.00% and 96.48% in ycN0 and ycN+ patients, respectively (p=0.159). Notably, patients with one NAAS node with ITC or micrometastasis in the entire population showed no further positive disease at ALND. Conclusion: NAAS showed excellent and stable performance with a low FNR and high accuracy, indicating valuable application prospects in patients with breast cancer who received NAC. Patients with pre-NAC cN2-3 stages also have a chance to undergo NAAS, and the application of NAAS appears to be feasible regardless of the ycN stage. Especially for ycN0 population, there is no chance for NAAS to miss positive axillary lymph nodes. In addition, patients who had one NAAS node with ITC or micrometastasis might avoid ALND. Diagnostic performance of nanoparticle-assisted axillary staging in pre-neoadjuvant chemotherapy cN1, cN2 and cN3 patients Diagnostic performance of nanoparticle-assisted axillary staging in ycN0 and ycN+ patients Additional axillary disease at axillary lymph node dissection in patients with positive NAAS nodes after neoadjuvant chemotherapy XX- XX XX- XX XX- XX Citation Format: Ruixian Chen, Tao He, Jiqiao Yang, Shan Lu, Yunhao Wu, Chihua Wu, Ruoning Yang, Weijing Liu, Ya Huang, Xiangyue Meng, Xin Zhao, Qintong Li, Xin Sun, Jing Jing, Jie Chen. Implementation of nanoparticle-assisted axillary staging: reduced axillary intervention for patients with node-positive breast cancer following neoadjuvant therapy [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 PO3-22-09.

Abstract PO4-23-01: Imaging tailored axillary approach combined with radiotherapy eliminates axillary lymph node dissection in low-volume axillary disease after neoadjuvant chemotherapy

Abstract ABSTRACT Background Individualized treatment strategies are highlighted for breast cancer patients in the last decades. Therefore aggressive surgical approaches have begun to evolve towards minimally invasive tailored interventions. SLNB is widely used in patients who received neoadjuvant treatment (NAC) and axillary lymph node dissection (ALND) is recommended for patients with axillary residual disease after NAC. In our study, we investigated regional recurrence rates in patients with limited axillary residual disease after NAC who underwent imaging-guided (MR+USG) axillary surgery plus radiotherapy (RT) instead of ALND. Materials and Methods 139 patients whose clinical stages were T1-3 and N1 at the time of diagnosis, who had a clinically good or complete axillary response after neoadjuvant therapy, and who had axillary residue (≤3 pathological lymph nodes) with favorable response to NAC (&amp;gt;50% fibrotic changes) in the final pathological examination were included in the study. The tumor stage and the number of pathological lymph nodes were assessed by USG, MMG, MR, and PET-CT examination (The minimum number of lymph nodes to be removed was determined according to imaging findings). All patients underwent imaging-guided SLNB (blue dye) and imaging-guided palpable lymph node excision. The patients were re-evaluated with their final pathology results in the multidisciplinary councils for suitable further treatments, ALND or RT. Peripheral lymphatic radiotherapy was applied to patients whose radiology and pathology results were compatible and no further surgery was done. The patients whose radiologically detected number of positive nodes was inconsistent with the number of metastases in pathology examination and who were presumed to have the gross residual disease underwent ALND. These patients were excluded from the study. Results The median age was 47 years. The median number of lymph nodes excised was 4. The total number of excised lymph nodes was between 1-3 in 64 (46%) patients and between 4-6 in 62 (45%) patients. 13 (9%) patients had ≥7 lymph nodes. 1 metastatic lymph node was found in all patients with 1 positive lymph node according to imaging findings. Of 41 patients with 2 radiologically positive lymph nodes, 1 metastatic lymph node was found in 17 (41%) patients, 2 metastatic lymph nodes in 22 (53%), and 3 metastatic lymph nodes in 2 (5%) patients respectively. Radiology reported 3 positive lymph nodes in 22 patients, of which 1 metastatic lymph node was found in 8 (36%), 2 metastatic lymph nodes in 10 (45%), and 3 metastatic lymph nodes in 4 (18%). The median follow-up period was 44 months. One patient had breast recurrence at the 31st month and one patient had lymphatic recurrence in the supraclavicular area at the 39th month. Systemic recurrence was noted in 6 (4.3%) patients. No axillary recurrence occurred during the follow-up period. Conclusions Patients with pathological-suspicious ≤ 3 lymph nodes shown by imaging (USG, MR, and PET-CT) who responded to NAC but still have residual disease in the axilla can be safely treated with SLNB(blue dye)+imaging-guided axillary approach and adjuvant RT. This approach eliminates the need for ALND in patients with low-volume residual axillary disease. Table. Patient characteristics Citation Format: Mahmut Muslumanoglu, Baran Mollavelioglu, Selman Emiroglu, Hasan Karanlik, Mustafa Tukenmez, Kamuran Ibis, Aysel Bayram, Ravza Yılmaz, Neslihan Cabıoğlu, Abdullah Igci. Imaging tailored axillary approach combined with radiotherapy eliminates axillary lymph node dissection in low-volume axillary disease 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 PO4-23-01.

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 PO5-11-11: Risk Assessment, Prevention and Early Detection of Breast Cancer Related Lymphedema – Objective Measurements and Patient Reported Outcomes

Abstract Background Breast cancer-related lymphedema (BCRL) affects the quality of life, but there is no consensus regarding early detection and monitoring. Patient-reported outcomes (PROs) are important in assessing cancer survivor outcomes, and different questionnaires have been developed. LYMPHA (Lymphatic Microsurgical Preventive Healing Approach) and S-LYMPHA (Simplified LYMPHA) have reduced BCRL rates. This study aims to identify the most reliable PRO in a South Florida multi-ethnic population and to study correlations between PROs and objective measurements in the first 6 months after axillary surgery. Methods Patients undergoing axillary lymph node dissection (ALND) or axillary radiation were included. L-Dex score (Bioimpedance Spectroscopy) and three validated questionnaires (LyQLI, Lymphedema Quality of Life Inventory; LyQOL, Lymphedema Quality of Life and FACT-B4+ Functional Assessment of Cancer Therapy – Lymphedema) were recorded at baseline, and 6 months post-surgery to assess the agreement between patient-reported symptoms and BCRL. L-Dex score outside the normal range or a 10 unit increase above baseline was considered lymphedema. Additional variables such as demographics, tumor characteristics, and treatment modalities were recorded. Results Out of 40 recruited patients, 39 were analyzed (excluding one deceased patient). Patient and treatment characteristics are described in Table 1. Patients were divided into three cohorts (Figure 1) for analysis: ALND with no axillary radiation (7.69%; n=33), Sentinel Lymph Node Biopsy (SLNB) with axillary radiation (7.69 %; n=3), and ALND with axillary radiation (85%; n=3). In the first cohort, LYMPHA or S-LYMPHA were associated with lower rates of lymphedema (19% vs, 50%) (p=0.116). No patients in the second or third cohort developed lymphedema. There were 4 out of 20 (20%) patients with lymphedema with scores above the median for FACT B4+ (p= 0.480) and a lower score (higher quality of life) correlated with lower L-Dex (p=0.76). The higher value in the physical domain of LyQLI showed higher L-Dex (p=0.826). There was a significant inter-domain correlation in LyQLI and LyQOL (p= &amp;lt; 0.001). Conclusion These results validate the use of PROs alongside objective measurements to assess BCRL. In addition, LYMPHA and S-LYMPHA significantly reduce lymphedema rates. Larger numbers will be necessary to reach statistical significance and to identify the best PRO. Figure 1 Division of patient population into three cohorts Table 1 Demographic and Treatment Summary Citation Format: Anshumi Desai, Orli-Friedman Eldar, Gili Halfteck, Mecker Moller, Susan Kesmodel, Dido Franceschi, Neha Goel, Jessica Crystal, Laura Huang, Jennifer Hu, Koru-Sengal Tulay, Wei Zhao, Alexis Narvaez-Rojas, Eli Avisar. Risk Assessment, Prevention and Early Detection of Breast Cancer Related Lymphedema – Objective Measurements and Patient Reported Outcomes [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 PO5-11-11.

Abstract PO3-02-08: Risk factors and a new predictive nomogram for predicting the Non-sentinel Lymph Node Metastasis in 708 early-stage Breast Cancer Patients with Positive Sentinel Nodes in China

Abstract Objective: The management of positive sentinel lymph node biopsies (SLNB) in patients with early-stage breast cancer remains a matter of controversy. Some studies have shown that not all breast cancer patients with positive sentinel lymph nodes (SLNs) benefit from further axillary lymph node dissection (ALND). Our study aims to analyse the risk factors and construct a new nomogram to predict non-sentinel lymph node (NSLN) metastasis in Chinese early-stage breast cancer patients with positive sentinel lymph nodes. Methods: The clinical data of 708 patients with early-stage breast cancer who attended The Fourth Hospital of Hebei Medical University for surgical treatment from January 2016 to December 2021 was retrospectively analyzed. All of them were female breast cancer patients with positive sentinel lymph nodes and underwent ALND. The patients were divided into modeling group and validation group according to the time of treatment. The patients in the modeling group were divided into a positive NSLN group and a negative NSLN group. The characteristics: age, maximum tumor diameter, the number of positive SLNs, proportion of positive SLNs, vessel carcinoma embolus, nerve invasion, status of ER, PR, HER-2 and Ki-67 were included in the analysis. And the independent risk factors of NSLN metastasis were screened by univariate (chi-square test) and multivariate (logistic regression) analysis. A nomogram model was established according to the screened independent risk factors, and the model was externally validated by the validation group. The ROC curve was plotted to calculate the area under the curve (AUC) and evaluate the predictive power of the nomogram model. A calibration curve and decision curve analysis (DCA) were used to evaluate the performance of the model. Results: Among the 708 patients, (modeling group n=410, validation group n=298), the average age, average number of positive SLNs, and NSLN positive rate were 50.9±11.1, 1.55±0.87 and 25.71%. The univariate analysis revealed statistically significant differences in the number of positive SLNs (P&amp;lt; 0.001), the proportion of positive SLNs (P &amp;lt; 0.001), vessel carcinoma embolus (P=0.001), nerve invasion (P=0.012), and ER status (P=0.029) in the NSLN-positive group compared with the negative group. The multifactorial logistic regression analysis revealed that the number of positive SLN (P=0.002; OR: 1.700; 95% CI: 1.219-2.370), the proportion of positive SLN (P=0.048; OR: 3.214; 95% CI: 1.001-10.490), vessel carcinoma embolus (P=0.010; OR: 2.076; 95% CI: 1.194-3.612), nerve invasion (P=0.024; OR: 2.119; 95% CI: 1.221-3.678), and ER status (P=0.045; OR: 2.978; 95% CI: 1.022-8.675) were independent risk factors for NSLN positivity. Furthermore, the nomogram was built using these 5 factors and validated on 298 patients in the validation group. The AUC was 0.728 (P&amp;lt; 0.001; 95%CI: 0.673-0.784) in the modeling group and 0.810 (P&amp;lt;0.001; 95%CI: 0.735-0.886) in the validation group. The calibration curves of the modeling and validation groups were close to the ideal curve, and DCA also showed that the model could be applied in clinical practice. Conclusion: For early-stage breast cancer with positive SLNs, these factors as the positive number of SLNs &amp;gt; 2, the ratio of positive SLNs &amp;gt; 50%, vessel carcinoma embolus, nerve invasion and ER-positive could predict NSLN metastasis well. The proposed nomogram appears to accurately estimate the likelihood of positive NSLNs and may greatly help the surgeon to decide intraoperatively whether to perform further ALND and avoid non-essential ALND as well as postoperative complications. Citation Format: Zhenchuan Song, Xueyi Zhao, Liu Yang. Risk factors and a new predictive nomogram for predicting the Non-sentinel Lymph Node Metastasis in 708 early-stage Breast Cancer Patients with Positive Sentinel Nodes in China [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 PO3-02-08.

Abstract PO3-07-07: Predictive Modeling for Identifying Breast Cancer Patients Eligible for Axillary Lymph Node Dissection Exemption Following Neoadjuvant Therapy: A Longitudinal MRI-based Radiomics and Deep Learning Features Analysis

Abstract Objective: Neoadjuvant therapy (NAC) has emerged as a pivotal treatment modality for breast cancer. However, accurately identifying patients who can safely avoid axillary lymph node dissection (ALND) following NAC remains challenging. In this study, our aim was to develop a predictive model using longitudinal MRI-based radiomics and deep learning features to identify breast cancer patients suitable for exemption from ALND. Methods: A total of 140 patients with cN1-2 breast cancer who underwent NAC were included in this study between January 2021 and October 2022. MRI images were collected before and after two cycles of NAC. The dataset was randomly divided into training and validation sets using a 7:3 ratio. Logistic regression (LR), K-nearest neighbors (KNN), LightGBM, and multilayer perceptron (MLP) machine learning models were utilized to predict axillary lymph node pathological complete response (ypN0) in patients following NAC. Finally, a prediction model with a single modality feature was trained by integrating all the extracted data. Results: Among the 140 patients included, 55 achieved ypN0 following NAC, while 85 did not achieve ypN0. Modeling the features extracted from pre- and post-chemotherapy evaluations revealed that the LR model achieved the highest area under the curve (AUC) values, reaching 0.842 and 0.841, respectively. Moreover, by integrating the evaluation of pre- and post-chemotherapy images and the net change of features between the two time points, the novel developed Amalgamation model demonstrated the highest AUC value of 0.958. The Amalgamation model exhibited an accuracy of 0.9, sensitivity of 0.833, and specificity of 1. Conclusion: Our study developed a predictive model using MRI images obtained before and after two cycles of NAC to identify breast cancer patients with ypN0 at an early stage. This model has the potential to avoid unnecessary ALND, significantly reducing complications. Keywords: breast cancer, neoadjuvant chemotherapy, axillary lymph node dissection, MRI, radiomics, deep learning, predictive modeling Figure 1: The ROC curves of Amalgamation model, Delta-model, Two-cycle reassessment-model and Baseline-model based on Logistic regression. Table 1: Performances of combining different machine learning models for predicting axillary lymph node pathological complete response to neoadjuvant therapy in pre- and post-neoadjuvant therapy MRI images. Citation Format: Yushuai Yu, Jialu Yi, Ruiliang Chen, Kaiyan Huang, Jie Zhang, Chuangui Song. Predictive Modeling for Identifying Breast Cancer Patients Eligible for Axillary Lymph Node Dissection Exemption Following Neoadjuvant Therapy: A Longitudinal MRI-based Radiomics and Deep Learning Features Analysis [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 PO3-07-07.