Axillary Recurrence Rate Research Articles

Combined analysis of the MF18-02/MF18-03 NEOSENTITURK studies: ypN-positive disease does not necessitate axillary lymph node dissection in patients with breast cancer with a good response to neoadjuvant chemotherapy as long as radiotherapy is provided.

The omission of axillary lymph node dissection (ALND) remains controversial for patients with residual axillary disease after neoadjuvant chemotherapy (NAC), regardless of the residual burden. This study evaluated the oncologic safety and factors associated with outcomes in patients with residual axillary disease. These patients were treated solely with sentinel lymph node biopsy (SLNB) or targeted axillary dissection (TAD), without ALND, after NAC. A joint analysis of two different multicenter cohorts-the retrospective cohort registry MF18-02 and the prospective observational cohort registry MF18-03 (NCT04250129)-was conducted between January 2004 and August 2022. All patients received regional nodal irradiation. Five hundred and one patients with cT1-4, N1-3M0 disease who achieved a complete clinical response to NAC underwent either SLNB alone (n=353) or TAD alone (n=148). At a median follow-up of 42 months, axillary and locoregional recurrence rates were 0.4% (n=2) and 0.8% (n=4). No significant difference was found in disease-free survival (DFS) and disease-specific survival (DSS) rates between patients undergoing TAD alone versus SLNB alone, those with breast positive versus negative pathologic complete response, SLN methodology, total metastatic LNof one versus ≥2, or metastasis types as isolated tumor cells with micrometastases versus macrometastases. In the multivariate analysis, patients with nonluminal pathology were more likely to have a worse DFS and DSS, respectively, without an increased axillary recurrence. The omission of ALND can be safely considered for patients who achieve a complete clinical response after NAC, even if residual disease is detected by pathologic examination. Provided that adjuvant radiotherapy is administered, neither the SLNB method nor the number of excised LNs significantly affects oncologic outcomes.

Significance of Residual Nodal Disease in Clinically Node-Negative Breast Cancer After Neoadjuvant Chemotherapy.

Trials evaluating omission of axillary dissection (ALND) in patients with cN0 breast cancer with positive sentinel lymph nodes (SLNs) haveexcluded neoadjuvant chemotherapy (NACT). It remains unclear whether the data can be extrapolated to cN0 patients undergoing NACT. This study sought to identify factors associated with positive SLNs and additional disease on ALND in cT1-2N0 disease after NACT. The authors queried their database for cT1-2N0 patients treated with NACT followed by SLN biopsy from 1996 to 2022. Physical examination and ultrasound determined clinical nodal status. Multivariable logistic regression identified factors associated with positive SLNs and disease on ALND. Of 1930 patients, 234 (12.1%) had positive SLNs. Positive SLNs were predicted by hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) status (odds ratio [OR] 2.5; p < 0.0001), lobular histology (OR 1.8; p = 0.007), multifocality (OR 2; p = 0.001), grade 1 tumors (OR 2.5; p = 0.002), and cT2 category (OR 1.9; p = 0.004). Of the 234 patients with positive SLNs and known SLN metastasis size, 148 (63.2%) underwent ALND, and 39 (26.4%) had additional positive nodes. Increasing patient age predicted disease on ALND (OR 1.03; p = 0.02). No additional positive nodes on ALND were identified in patients with only isolated tumor cells compared with 12.3% who had micrometastases and 37.6% who had macrometastases (p = 0.01). During a 5-year median follow-up period of the SLN-positive patients, three (1.3%) experienced axillary recurrence and twoof the three underwent ALND at the initial surgerywith no additional positive nodes. In cT1-2N0 breast cancer, HR+/HER2- status, lobular histology, multifocality and cT2 category predicted positive SLNs after NACT. Older age predicted positive nodes on ALND. Patients with positive SLNs had low axillary recurrence rates. These findings support investigation into omission of ALND in cN0 breast cancer and a low volume of SLN disease after NACT.

Excluding Upper Axillary Level 1 in Regional Nodal Irradiation Does Not Increase Axillary Recurrence Risk in Patients With Breast Cancer

PurposeThe optimal extent of regional nodal irradiation (RNI) in postoperative radiotherapy for breast cancer, particularly regarding axillary level 1 (AXL1), remains uncertain. This study aims to compare clinical outcomes between extensive RNI including the entire axilla and limited RNI excluding the upper AXL1 in patients with breast cancer. MethodsA retrospective analysis included 1,780 women with non-metastatic unilateral breast cancer who underwent RNI during postoperative radiotherapy between 2007 and 2018. Patients were classified into extensive and limited RNI groups based on the upper AXL1 inclusion in the radiation field. Propensity score matching yielded a cohort of 1,020 patients. Non-inferiority of limited RNI compared to extensive RNI was assessed with a defined margin of ≤2% in the 5-year axillary recurrence rate. ResultsAfter a median follow-up of 67.9 months, the 5-year axillary recurrence rates were similar between extensive and limited RNI groups (1.2% vs. 1.6%; Plog-rank=0.790). Limited RNI demonstrated non-inferiority with a 0.4% difference (95% confidence interval, -1.1%–1.9%; Pnon-inferiority=0.019). Disease-free survival (87.9% vs. 91.5%; Plog-rank=0.122) and overall survival (94.1% vs. 96.9%; Plog-rank=0.260) at 5 years were not significantly different between extensive and limited RNI groups. Multivariable analysis revealed that lymphovascular invasion (hazard ratio [HR], 5.17; P=0.02) and negative hormone receptor status (HR, 11.73; P=0.002) were associated with a higher risk of axillary recurrence, while limited RNI showed no significant association (HR, 1.35; P=0.652). Subgroup analysis demonstrated that extensive RNI did not improve axillary control in patients with lymphovascular invasion, hormone receptor negativity, positive lymph node metastasis, or a small number of nodes removed. ConclusionLimited RNI, excluding the upper AXL1 from the radiation field, demonstrated axillary recurrence rates comparable to those of extensive RNI in patients with breast cancer. The study suggests that extensive RNI may not provide additional therapeutic benefits, while limited RNI appears to be a valid option for regional control.

ThP2.4 - Unveiling the Odds: Identifying the Axillary Recurrence rates in Invasive Breast Cancer Surgery in a district general hospital - Seventeen years of Surgical Performance decoded

Abstract Introduction Axillary recurrence should be minimised by effective staging and treatment where appropriate Minimum standard &amp;lt;5% axillary recurrence at 5 years Target &amp;lt;3% axillary recurrence at 5 years according to UK ABS guidelines. Methods All patients with primary cancer diagnosed at our institution between January 2004 and December 2020 were identified from a prospectively maintained database of operations obtained from the medical coding department. Demographics of the patients, pre-operative investigations, MDT discussion outcomes, operative details (and complications), post-operative pathology, neo-adjuvant and adjuvant therapy regimens and follow-up data were recorded. All patients were followed up to the censoring date of December 2021 which gave a median follow-up of 18 months (range, 12- 204). Axillary recurrence and treatment regimens were recorded. Primary outcome measures were overall axillary recurrence and disease-free. IBM SPSS Statistics (Version 26.0 (IBM Corporation, Armonk, NY, USA) was used for statistical analysis to determine patient and pre-operative pathological characteristics that were predictive of isolated axillary recurrence after completion of the primary treatment course. Significance was defined as P&amp;lt;0.05. Results There were 4024 women diagnosed with breast cancer in Midyorks trust between this period who were referred and had surgical intervention. Of these, 107 patients were identified with recurrences. 12 were found to have an isolated axillary recurrence (8 ANC 4 SLNB) Conclusion The 17-year isolated axillary recurrence rate of women treated was 0.3%. Multimodality management at the time of recurrence, including axillary surgery, radiation, and systemic therapy, significantly improved the morbidity

Axillary Recurrence in Sentinel Lymph Node Negative Mastectomy Patients at 16 Years Median Follow Up: Natural History in the Absence of Radiation

BackgroundAxillary recurrence following lumpectomy with a negative sentinel lymph node biopsy (SLNB) is rare, possibly due to routine use of whole breast radiation. In this study, we characterized the rate of any axillary recurrence among mastectomy patients with a negative SLNB and no adjuvant radiation therapy. MethodsWe identified women who underwent mastectomy with SLNB for early-stage breast cancer (1999-2005) and included patients with pathologically negative nodes and no axillary dissection or adjuvant radiation. The primary outcome was ipsilateral axillary recurrence. ResultsA total of 234 women, median age 50 years, underwent 242 mastectomies. Histology showed 112 (46%) invasive cancers, 16 (7%) ductal carcinoma in-situ (DCIS) with microinvasion, and 114 (47%) pure DCIS. Cancers were predominantly estrogen receptor positive (59%) and moderate (41%) or high grade (32%). A mean of 2 final sentinel nodes were excised (range 1-6) and 21 patients (9%) had isolated tumor cells on SLNB pathology. At 16 years median follow up (range 1-22 years), 3 patients (1.2%) developed an isolated axillary failure, and 1 had concurrent axillary and chest wall recurrences (total axillary recurrence rate 1.7%). Three of four axillary recurrences occurred in patients with moderate or high-grade estrogen receptor-positive DCIS without invasion on mastectomy histology. Median time to axillary recurrence was 70.5 months (range 29-132 months). ConclusionsAxillary recurrence is rare after a negative SLNB, even in the absence of adjuvant radiation. This supports the safety of forgoing additional surgery or radiation to the axilla in the early-stage breast cancer and a negative SLNB.

Oncologic outcome of response-guided axillary treatment in patients with cN1 breast cancer after primary systemic therapy.

514 Background: In breast cancer, the majority of clinically node positive (cN1) patients are treated with primary systemic treatment (PST), with increasing rates of axillary pathologic complete response (pCR). Evidence supporting tailoring axillary treatment according to the response is growing. However, it is still debatable whether ALND is beneficial in cN1 patients with residual nodal disease and if any further axillary treatment is necessary in patients achieving pCR. In this study, we present the four-year oncologic outcome of cN1 patients undergoing either axillary radiation treatment or no axillary treatment according to the ‘Marking Axillary lymph nodes with Radioactive Iodine seeds’ (MARI)-protocol. Methods: Between 2014 and 2021, we prospectively enrolled patients with node positive breast cancer and 1 - 3 involved axillary lymph nodes on FDG-PET/CT pre-PST, who were treated according to the MARI-protocol. Patients with residual disease of the MARI node (ypN1) received axillary radiotherapy (RT), while patients with a pCR of the MARI node (ypN0) received no further axillary treatment. The primary endpoint was the axillary recurrence rate. Secondary endpoints include invasive disease free survival (iDFS) and overall survival (OS), calculated using the Kaplan-Meier method. Results: Of the 367 included patients, more than half (54%, n= 198) had hormonal receptor positive (HR+)/Human Epidermal growth factor 2 negative (HER2-) breast cancer; 59 patients (16%) had HR+/HER2+; 39 patients (11%) had HR-/HER2+ and 71 patients (19%) had triple negative (TN) subtype. Median age was 49 (IQR 41 – 56) years. 231 (63%) patients who had ypN1 received RT and 136 patients (37%) who achieved ypN0 received no further axillary treatment. Median follow up was 49 (IQR 32 – 70) months. Axillary recurrence rate was 3.5% ( n= 8) in patients with ypN1 and 0.7% ( n= 1) in patients with ypN0. Most axillary recurrences ( n= 6) occurred simultaneously with distant metastases in the ypN1 group. In patients with ypN1, the iDFS was 86% and the OS 93%; in ypN0 patients, the iDFS was 93% and the OS 98%. Conclusions: Response-guided axillary treatment in patients with limited nodal disease according to the MARI protocol is associated with favorable oncologic outcome without performing ALND’s. De-escalation can therefore be considered safe. [Table: see text]

Abstract PS01-02: Long-term outcomes of sentinel lymph node biopsy following neoadjuvant chemotherapy for initially node-positive breast cancer: A systematic review and meta-analysis

Abstract Background: Sentinel lymph node biopsy (SLNB) alone is now frequently offered to women with initially node-positive breast cancer who convert to pathologically node negative (nodal pCR) following neoadjuvant chemotherapy (NAC), despite limited long-term data regarding the oncologic safety of this approach. The aim of this meta-analysis was to evaluate the long-term oncologic outcomes associated with SLNB alone following NAC for initially node-positive breast cancer. Methods: A systematic review and meta-analysis was conducted according to PRISMA guidelines. Medline (Ovid), Embase, and Cochrane Central Registry were systematically searched for studies comparing women undergoing SLNB or ALND following NAC for initially clinically node-positive breast cancer. Included studies reported one of the following outcomes: axillary recurrence (AR), locoregional recurrence (LRR), disease-free survival (DFS) or overall survival. A random effects meta-analysis was used to calculate weighted pooled effect estimates (risk ratios, RR) for all outcomes. Variability across studies due to heterogeneity was estimated using I2 statistics. Subgroup analysis was performed by length of follow-up for each study. Risk of bias within studies was assessed using the Newcastle-Ottawa Scale (NOS). Results: Data for participants undergoing treatment between 2004 and 2022 was captured across studies. The median age of women treated with NAC for initially node-positive breast cancer ranged from 46 to 60 years. The median follow-up time ranged from 19.5 to 108 months across included studies. Nine observational studies were eligible for meta-analysis. No studies were excluded from the analysis on the basis of quality: Newcastle-Ottawa Scale scores ranged from 6 to 9 (maximum possible score of 9). Rates of axillary recurrence (AR) were low across all included studies (range 0.0% to 5.6%). For AR, data for 2,882 patients from 7 studies was quantitatively synthesized (SLNB=1,964; ALND=917). For LRR, data for 2,629 patients from 7 studies was quantitatively synthesized (SLNB=1,857; ALND=771). No significant differences were observed in AR between patients undergoing SLNB alone versus ALND following NAC for initially node-positive breast cancer: pooled RR 1.02 (95% CI: 0.46-2.29, I2=0.0%). Similarly, no significant differences were observed in LRR (RR 0.70, 95% CI: 0.45-1.10, I2=0.0%), DFS (RR 0.77, 95% CI: 0.55-1.08, I2=0.0%), nor overall mortality (RR 0.66, 95% CI: 0.33-1.33, I2=0.0%) between the SLNB and ALND groups. Conclusions: Among patients who convert to node-negative following NAC, this meta-analysis suggests that SLNB alone does not result in significantly different oncologic outcomes compared to ALND, and that de-escalation of axillary surgery to SLNB alone in this context may be safely considered in this patient population. Citation Format: Mariam Rana, Anna Weiss, Alison Laws, Carol Mita, Tari King. Long-term outcomes of sentinel lymph node biopsy following neoadjuvant chemotherapy for initially node-positive breast cancer: A systematic review and meta-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 PS01-02.

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 PS01-03: What to expect from the No axillary surgical treatment for lymph node-negative patients after ultra-sonography [NAUTILUS] trial (KBCSG-21): Clinicopathologic characteristics and axillary lymph node status of enrolled patients

Abstract Purpose: The primary role of sentinel lymph node biopsy (SLNB) for early breast cancer (BC) is axillary staging. In terms of clearance of axillary disease or prevention of recurrence, its role may be limited considering the low axillary recurrence rate of less than 2% even though false-negative rates are 5-10% and the 25% additional axillary lymph node (ALN) detection in the ALND arms of the ACOSOG Z0011 and AMAROS trials. The NAUTILUS trial (NCT04303715) randomized cT1-2/N0 BC patients planned for breast-conserving surgery to evaluate the non-inferiority of omitting SLNB regarding 5-year invasive disease-free survival. The secondary endpoints are overall survival, distant metastasis-free survival, axillary recurrence rate, and quality of life of the patients. We aimed to investigate the clinicopathologic characteristics and ALN status of the subjects enrolled in the NAUTILUS trial. Methods: NAUTILUS trial randomized 1,734 subjects into SLNB or no-SLNB arms from September 2020 to October 2022. Axillary ultrasonography was mandatory to determine clinical N0, defined as no suspicious ALN or no tumor on ultrasound-guided biopsy of suspicious ALN. Clinicopathologic variables and the ALN status of the SLNB arm were analyzed. Results: Among 1,734 enrolled subjects, 828 (50.3%) and 818 (49.7%) subjects in the SLNB and no-SLNB arms, respectively, were included for analysis. Clinical and pathologic T stage, hormonal receptor/HER2 status, histologic grade, age, menopausal status, and Ki-67 were evenly distributed between the two groups (p = 0.554, 0.350, 0.056, 0.369, 0.623, 0.725 and 0.214, respectively). Median age was 55.3 (range, 48.0-62.0) years, and 661 (40.2%) were premenopausal. Overall, 30 (1.8%), 1,382 (84.0%), and 229 (13.9%) subjects were pTmic, pT1, and pT2, respectively, and median tumor size was 1.3 cm (range, 0.1-5.0). In the SLNB group, 94 (11.4%) had ALN metastasis, of which 9 (1.1%), 78 (9.4%), and 5 (0.6%) were pN1mic, pN1, and pN2-3, respectively (Table 1). According to pathologic tumor size, 5.8% (16/279), 11.4% (48/421), and 23.8% (30/126) were ALN positive for ≤ 1.0 cm, &amp;gt;1.0cm &amp; ≤ 2.0 cm, and &amp;gt; 2.0 &amp; ≤ 5.0 cm, respectively. The clinical and pathologic tumor size distribution among subjects with ALN metastasis were 23 (24.5%), 43 (45.7%), 9 (9.6%) and 16 (17.0%), 48 (51.1%), 30 (31.9%), respectively, for ≤ 1.0 cm, &amp;gt;1.0cm &amp; ≤ 2.0 cm, and &amp;gt; 2.0 &amp; ≤ 5.0 cm (Table 2). Among them, 12 (12.8%) received subsequent ALND. There was no difference in ALN metastasis rate according to molecular subtype, histologic grade, age, menopausal status, and Ki-67 (p= 0.812, 0.204, 0.671, and 0.101, respectively). Conclusions: The NAUTILUS trial completed enrollment of 1,734 subjects, among which 1,646 are available to analyze basic clinicopathologic characteristics. The trial included 229 (13.9%) pT2 and 661 (40.2%) premenopausal subjects and is expected to show the impact of SLNB omission in these subgroups. Data lock is expected in October 2027. Patients characteristics SLNB, sentinel lymph node biopsy; LVI, lymphovascular invasion; IDC, invasive ductal carcinoma; ILC, invasive lobular carcinoma; HER2, anti-human epidermal growth factor-2; BCS, breast conserving surgery; TM, total mastectomy; ALND, axillary lymph node dissection Basic characteristics for sentinel lymph node biopsy group a revealed no lymph node metastasis by fine needle aspiration or gun biopsy ALN, axillary lymph node; LN, lymph node Citation Format: Jai Min Ryu, Han-Byoel Lee, Sei Hyun Ahn, Il-Yong Chung, Seeyoun Lee, Seho Park, Woosung Lim, Joon Jeong, Jeong Eon Lee, Eunhye Kang, Ji Hyun Chang, Jung Min Chang, Woo Kyung Moon, Wonshik Han, Eun-Kyu Kim. What to expect from the No axillary surgical treatment for lymph node-negative patients after ultra-sonography [NAUTILUS] trial (KBCSG-21): Clinicopathologic characteristics and axillary lymph node status of enrolled patients [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 PS01-03.

Abstract PO4-19-04: AXSANA – EUBREAST-3: An international prospective multicenter cohort study to evaluate different surgical methods of axillary staging in clinically node-positive breast cancer patients treated with neoadjuvant chemotherapy

Abstract Background The optimal surgical staging procedure of the axilla in patients who convert from a clinically positive (cN+) to a clinically negative node status (ycN0) through neoadjuvant chemotherapy is still controversial. Widely diverse techniques such as full Axillary Lymph Node Dissection (ALND), Targeted Axillary Dissection (TAD), Targeted Lymph Node Biopsy (TLNB) and Sentinel Lymph Node Biopsy (SLNB) alone are given preference in different international guidelines. So far, no comparative data on the oncological outcome or the morbidity of the different procedures are available. Further research is needed to safely de-escalate the extent of axillary surgery in this patient group. Trial design The AXSANA study is an international prospective cohort study including cN+ patients converting to ycN0 status and treated with different axillary staging techniques according to the standard at their treating institution. The study was initiated by the EUBREAST network. The trial includes patients with cT1-4c tumors, who present initially with axillary lymph node metastasis scheduled for neoadjuvant chemotherapy. According to an amendment in 2020 the inclusion of patients with highly suspicious nodes without confirmation using a minimally invasive biopsy is allowed. All patients converting to ycN0 status undergo follow-up for 5 years irrespectively of the ypN status. Primary endpoints: Invasive disease-free survival, axillary recurrence rate and health-related quality of life (HRQoL). HRQoL are evaluated using four standardized questionnaires (EORTC QLQ-C 30, EORTC QLQ-BR 23, Lymph ICF and SOC-13) at baseline and after 1, 3 and 5 years after surgery. Secondary endpoints are the feasibility and performance of different axillary staging techniques (detection rate, number of removed lymph nodes and association with complications, arm morbidity and quality of life, operating time and use of clinical and economic resources); impact of learning curve, and the detailed mapping of surgical and oncological treatment standards in different countries. The impact on different regional treatment strategies (radiotherapy, ALND) in patients with ypN0(i+), ypN1(mi) and ypN1 is assessed. Current status of the study: 4336 patients from 284 study sites and 26 countries were enrolled in the study between June 2020 and June 2023. Among 3722 patients with a defined surgical concept 1631 women were scheduled for TAD, 1483 for ALND, 469 for SLNB, 25 for TLNB and 109 for other procedures. A target lymph node was marked in 2309 patients, most frequently using clips/coils (1850, 80.1%), followed by magnetic seeds (219, 9.5%), carbon ink (171, 7.4%), radar marker (80, 3.5%), radioactive seeds (4, 0.2%) and other techniques (24, 1.0%). Funding: AGO-B, GBG, Claudia-von Schilling Foundation, Ehmann Foundation, Eugen und Irmgard Hahn Foundation, AWOgyn, Merit Medical, Endomagnetics, Mammotome Contact information: Prof. Dr. Thorsten Kühn Department of Gynecology and Obstetrics University of Ulm, Germany Baumreute 37 D-73730 Esslingen Germany E-Mail: kuehn.thorsten@t-online.de Citation Format: Thorsten Kühn, Steffi Hartmann, Elmar Stickeler, Jana de Boniface, Oreste Davide Gentilini, Sarah Fröhlich, Franziska Ruf, Marc Thill, Michael Hauptmann, Guldeniz Karadeniz Cakmak, Isabel Rubio, Maria Luisa Gasparri, Michalis Kontos, Eduard-Alexandru Bonci, Laura Niinikoski, Bilge Aktas Sezen, Rosa Di Micco, Dawid Murawa, Geeta Kadayaprath, David Pinto, Florentia Peintinger, Matilda Appelgren, Janine M. Simons, Marjolein Smidt, Ellen Schlichting, Lukas Dostalek, Elisabeth Thiemann, Markus Hahn, Michael Schrauder, Semra Gunay, Gunay Gurleyik, Nina Helidon, Hagigat Valiyeva, Ashutosh Kothari, Marian Vanhoeij, Andraz Perhavec, Tsvetomir Ivanov, Dov Zippel, Lia Rebaza, Sarun Thongvitokomarn, Sibylle Loibl, Maggie Banys-Paluchowski. AXSANA – EUBREAST-3: An international prospective multicenter cohort study to evaluate different surgical methods of axillary staging in clinically node-positive breast cancer patients treated with 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 PO4-19-04.

Abstract PS01-01: Feasibility and oncological safety of targeted axillary dissection or sentinel lymph node biopsy in patients with clinically node-positive disease after neoadjuvant chemotherapy in the prospective MF-1803 NEOSENTITURK-study

Abstract PS01-01: Feasibility and oncological safety of targeted axillary dissection or sentinel lymph node biopsy in patients with clinically node-positive disease after neoadjuvant chemotherapy in the prospective MF-1803 NEOSENTITURK-study

Abstract PO4-23-02: Blue Dye-Only for Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy in Patients with Initially Node-positive Breast Cancer

Abstract Importance: Randomized trials evaluated the false negative rate (FNR) of sentinel lymph node biopsy (SLNB) in initially node-positive (cN1/2) breast cancer (BC) patients who downstaged after neoadjuvant chemotherapy (NAC): the studies were negative, as they found FNR above 10%. However, the FNR was adequate when the lymph node was marked with a clip before NAC or at least 3 lymph nodes were removed. SLNB using a combination of blue dye and a radiotracer (Technetium-99) was encouraged to facilitate identification and maximize SLNB results in this scenario. However, radiotracer is unavailable in many services around the world, particularly in low- and middle-income countries (LMIC), but the feasibility and the recurrence rates of SNLB with the use of blue dye-only, in previous cN1/2 patients, are unknown. Objective: The aim of this study was to evaluate the feasibility, proportion of patients undergoing SLNB without axillary dissection (AD) and mean number of resected sentinel nodes (SN), and recurrence rates (axillary recurrence [AR], ipsilateral breast recurrence [IBR], new contralateral primary, disease-free survival [DFS] and overall survival [OS]) of SNLB with the use of blue dye-only in initially node-positive BC (cN1/2). Design, Setting, and Participants: From 2013 to 2023, a cohort of patients undergoing NAC was evaluated at a public institution in Brazil (Hospital Geral de Fortaleza - HGF). Radiotracer and clips were not available. Patients with prior cN1/2 were identified and evaluated. AD was not recommended in cases of negative histopathological results for lymph node metastases after SLNB using blue dye-only. Inflammatory, cN0 and cN3 BC patients were excluded. Results: Among 119 cN1/2 BC patients treated with NAC, 100 (84%) cases underwent SLNB with blue dye-only and 70 (59%) had SLNB alone. The median of SN were 3.1 and 55 (78%) cases had 3 or more SN. No events related to blue dye occurred. The median age of these 70 patients was 49 (25-84) years, and most cases were T2 (n=40/57.1%), followed by T3 (n=18/25.7%), T4 (n=6/8.6%) and T1 (n=6/8.6%), while N1 predominated in axillary status (n=64/91.4%). Regarding breast cancer subtype, there were 19 (27.1%) hormone receptor-positive/HER2-negative, 16 (22.9%) hormone receptor-negative/HER2-positive, 21 (30%) hormone receptor-positive/HER2-positive and 14 (20%) triple-negative cases. 55 (79%) patients received regimens containing anthracyclines and taxanes. Anti-HER2 therapy was used in all cases, but pertuzumab associated with trastuzumab were available in only 8 patients (8/37). Breast-conserving surgery was performed in 40 (57%) cases while total mastectomy in 30 (43%). Patients with hormone-positive BC received endocrine therapy. Adjuvant radiotherapy was made in all cases, except one who underwent mastectomy. After 36 months of median follow-up, no axillary recurrences were observed. One patient had a new primary in the contralateral breast. Three patients had distant disease and two died. Conclusions: This cohort found that the use of SLNB with blue dye-only in Initially cN1/2 BC patients who achieved complete response after NAC is feasible, with very low axillary recurrence rates, like previous reports in the literature that used a combination of tracers. These data reinforce the need for further studies in this scenario, as it maintains the possibility of avoiding AD in places with difficult access to oncological treatment, especially in LMIC. Figure 1 - Flowchart cN: Clinical node stage; BC: Breast cancer; NAC: Neoadjuvant chemotherapy; SNLB: Sentinel lymph node biopsy; AD: Axillary dissection; SN: Sentinel node Table 1 - Demographic Characteristics Citation Format: Francisco Pimentel Cavalcante, Felipe Zerwes, Alessandra Souza, Patricia Ziegelmann, Ryane Alcantara, Amanda Cardoso, Andre Mattar, Eduardo Millen, Antonio Frasson. Blue Dye-Only for Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy in Patients with Initially Node-positive Breast Cancer [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 PO4-23-02.

The use of blue dye alone for sentinel lymph node biopsy after neoadjuvant chemotherapy in patients with initially node-positive breast cancer

IntroductionFalse-negative sentinel lymph node biopsy (SLNB) rates following neoadjuvant chemotherapy (NACT) in initially node-positive (cN1/2) breast cancer patients are high, but decrease when lymph nodes are clipped, ≥3 sentinel lymph nodes (SLN) are removed or dual-tracer localization (radioisotope and blue dye) is used. Radiotracer, however, is often unavailable and outcomes with blue dye alone are unknown. Materials and methodsInitially cT1-4, cN1/2 patients treated with NACT in 2013–2023 who underwent SLNB using blue dye alone were evaluated regarding SLN identification, axillary recurrence, disease-free and overall survival rates. ResultsOf 119 patients included, 19 remained cN1/2 after NACT. SLNB was performed using blue dye alone in 100 ycN0 cases (84%), with an identification rate of 96%. The SLN was negative in 70/119 cases (i.e. 59% avoided axillary dissection). The number of SLN detected was ≥3 in 55/70 cases (78%) (median 3.1; 1–6). Median age was 49 years (25–84). Most were T2 (n = 40, 57.1%), N1 (n = 64, 91.4%). Predominant subtypes were ERBB2 (52.9%) and triple-negative (20%). No axillary recurrence occurred over a median 36-month period. Five-year disease-free and overall survival were, respectively, 85.9% (95%CI: 74–99.8) and 96.3% (95%CI: 89.4–100). The ERBB2 subtype (1.99, 95%CI: 1.02–3.85, p = 0.04) and N1 lymph node status (2.58, 95%CI: 1.54–9.10, p = 0.03) were associated with a greater likelihood of undergoing SLNB alone without axillary dissection. ConclusionsSLNB with blue dye alone following NACT in initially cN1/2 patients avoided axillary dissection in almost 60% of cases, with no recurrences during the period evaluated. Longer follow-up studies are necessary.

Quality assurance of radiation therapy after breast-conserving surgery among patients in the BOOG 2013-08 trial

Background and purposeIn the BOOG 2013-08 trial (NCT02271828), cT1-2N0 breast cancer patients were randomized between breast conserving surgery with or without sentinel lymph node biopsy (SLNB) followed by whole breast radiotherapy (WBRT). While awaiting primary endpoint results (axillary recurrence rate), this study aims to perform a quality assurance analysis on protocol adherence and (incidental) axillary radiation therapy (RT) dose. Materials and methodsPatients were enrolled between 2015 and 2022. Data on prescribed RT and (in 25% of included patients) planning target volumes (PTV) parameters were recorded for axillary levels I-IV and compared between treatment arms. Multivariable linear regression analysis was performed to determine prognostic variables for incidental axillary RT dose. Results1,439/1,461 included patients (98.5%) were treated according to protocol and 87 patients (5.9%) received regional RT (SLNB 10.9%, no-SLNB 1.5 %). In 326 patients included in the subgroup analysis, the mean incidental PTV dose at axilla level I was 59.5% of the prescribed breast RT dose. In 5 patients (1.5%) the mean PTV dose at level I was ≥95% of the prescribed breast dose. No statistically or clinically significant differences regarding incidental axillary RT dose were found between treatment arms. Tumour bed boost (yes/no) was associated with a higher incidental mean dose in level I (R2 = 0.035, F(6, 263) = 1.532, p 0.168). ConclusionThe results indicate that RT-protocol adherence was high, and that incidental axillary RT dose was low in the BOOG 2013-08 trial. Potential differences between treatmentarms regarding the primary endpoint can thus not be attributed to different axillary radiation doses.

Strict versus Liberal Use of Sentinel Node Biopsy in Breast Cancer Surgery: Any Clinical Outcome Differences? A 20-Year Clinical Experience

Introduction: As applied to early breast cancer (BC) patients, sentinel node biopsy (SNB) has undergone major changes over the years, especially concerning the widening of indication criteria or skipping systematic axillary lymph node dissection (ALND) after a positive SN. We aimed to ascertain whether a strict versus a more liberal use of SNB resulted in different clinical outcomes in our clinical experience. Methods: We studied consecutive BC patients undergoing SNB between January 1, 2000, and March 31, 2020. There were 1,587 patients and 1,634 SNB procedures. Cases were divided into two study groups: the “strict” SNB group (unifocal tumors up to 35 mm in which ALND was always performed for a positive SN, amounting to 1,183 SNBs), and the “liberal” SNB group (extended tumor size up to selected T3 cases, as well as multifocal or bilateral disease, and patients with previous contralateral BC, not always followed by ALND after a positive SN, amounting to 451 SNBs). Patients were closely followed up to the end of the study. Results: Clinico-pathological variables were strikingly different between study groups, with the liberal group showing a higher risk profile. Cox regression analysis for disease recurrence did not show significant differences in axillary, lymph node, or locoregional recurrence rates or distant relapse. There were no differences in survival between groups. Conclusion: It seems reasonable to adopt the liberal SNB approach, as the goal of surgical management in early BC patients must be attaining optimal locoregional disease control, no matter the differences in distant metastatic spread rates across different BC risk profiles.

Efficacy and safety comparison between axillary lymph node dissection with no axillary surgery in patients with sentinel node-positive breast cancer: a systematic review and meta-analysis

BackgroundThis systematic review and meta-analysis aimed to study the evidence on the efficacy and safety of omitting axillary lymph node dissection (ALND) for patients with clinically node-negative but sentinel lymph node (SLN)-positive breast cancer using all the available evidence.MethodsThe Embase, Medline, and Cochrane Library databases were searched through February 25, 2023. Original trials that compared only the sentinel lymph node biopsy (SLNB) with ALND as the control group for patients with clinically node-negative but SLN-positive breast cancer were included. The primary outcomes were axillary recurrence rate, total recurrence rate, disease-free survival (DFS), and overall survival (OS). Meta-analyses were performed to compare the odds ratio (OR) in rates and the hazard ratios (HR) in time-to-event outcomes between both interventions. Based on different study designs, tools in the revised Cochrane risk of bias tool were used for randomized trials and the risk of bias in nonrandomized studies of interventions to assess the risk of bias for each included article. Funnel plots and Egger's test were used for the publication’s bias assessment.ResultsIn total, 30 reports from 26 studies were included in the systematic review (9 reports of RCTs, 21 reports of retrospective cohort studies). According to our analysis, omitting ALND in patients with clinically node-negative but SLN-positive breast cancer had a similar axillary recurrence rate (OR = 0.95, 95% confidence interval (CI): 0.76–1.20), DFS (HR = 1.02, 95% CI: 0.89–1.16), and OS (HR = 0.97, 95% CI: 0.92–1.03), but caused a significantly lower incidence of adverse events and benefited in locoregional recurrence rate (OR = 0.76, 95% CI: 0.59–0.97) compared with ALND.ConclusionFor patients with clinically node-negative but SLN-positive breast cancer (no matter the number of the positive SLN), this review showed that SLNB alone had a similar axillary recurrence rate, DFS, and OS, but caused a significantly lower incidence of adverse events and showed a benefit for the locoregional recurrence compared with ALND. An OS benefit was found in the Macro subset that used SLNB alone versus complete ALND. Therefore, omitting ALND is feasible in this setting.Trial registrationCRD 42023397963

Safety of Targeted Axillary Dissection After Neoadjuvant Therapy in Patients With Node-Positive Breast Cancer

The increasing use of neoadjuvant systemic therapy (NST) has led to substantial pathological complete response rates in patients with initially node-positive, early breast cancer, thereby questioning the need for axillary lymph node dissection (ALND). Targeted axillary dissection (TAD) is feasible for axillary staging; however, data on oncological safety are scarce. To assess 3-year clinical outcomes in patients with node-positive breast cancer who underwent TAD alone or TAD with ALND. The SenTa study is a prospective registry study and was conducted between January 2017 and October 2018. The registry includes 50 study centers in Germany. Patients with clinically node-positive breast cancer underwent clipping of the most suspicious lymph node (LN) before NST. After NST, the marked LNs and sentinel LNs were excised (TAD) followed by ALND according to the clinician's choice. Patients who did not undergo TAD were excluded. Data analysis was performed in April 2022 after 43 months of follow-up. TAD alone vs TAD with ALND. Three-year clinical outcomes were evaluated. Of 199 female patients, the median (IQR) age was 52 (45-60) years. A total of 182 patients (91.5%) had 1 to 3 suspicious LNs; 119 received TAD alone and 80 received TAD with ALND. Unadjusted invasive disease-free survival was 82.4% (95% CI, 71.5-89.4) in the TAD with ALND group and 91.2% (95% CI, 84.2-95.1) in the TAD alone group (P = .04); axillary recurrence rates were 1.4% (95% CI, 0-54.8) and 1.8% (95% CI, 0-36.4), respectively (P = .56). Adjusted multivariate Cox regression indicated that TAD alone was not associated with an increased risk of recurrence (hazard ratio [HR], 0.83; 95% CI, 0.34-2.05; P = .69) or death (HR, 1.07; 95% CI, 0.31-3.70; P = .91). Similar results were obtained for 152 patients with clinically node-negative breast cancer after NST (invasive disease-free survival: HR, 1.26; 95% CI, 0.27-5.87; P = .77; overall survival: HR, 0.81; 95% CI, 0.15-3.83; P = .74). These results suggest that TAD alone in patients with mostly good clinical response to NST and at least 3 TAD LNs may confer survival outcomes and recurrence rates similar to TAD with ALND.

The Axillary Lateral Vessel Thoracic Junction Is Not an Organ at Risk for Breast Cancer–Related Lymphedema

Breast-cancer related lymphedema (BCRL) is a treatment complication that significantly reduces patient quality of life. Regional nodal irradiation (RNI) may increase the risk of BCRL. Recently, a region of the axilla known as the axillary-lateral thoracic vessel juncture (ALTJ) was identified as a potential organ-at-risk (OAR). Here, we set to validate whether radiation dose to the ALTJ is associated with BCRL. We identified patients with stage II-III breast cancer treated with adjuvant RNI from 2013-2018, excluding those with BCRL pre-radiation. We defined BCRL as difference in arm circumference between the ipsilateral and contralateral limb >2.5 cm at any 1 encounter or ≥2 cm on ≥2 visits. All patients suspected of having BCRL at routine follow-up visits were referred to physical therapy for confirmation. The ALTJ was retrospectively contoured, and dose metrics were collected. Cox proportional hazards regression models were used to test the association between clinical and dosimetric parameters with the development of BCRL. Population includes 378 patients with median age 53 years, median body mass index (BMI) 28.4 kg/m2, 71% underwent mastectomy, and median 18 axillary nodes removed. Median follow-up was 70 months (IQR, 55-89.7 months). BCRL developed in 101 patients at a median of 18.9 months (IQR, 9.9-32.4 months) with a corresponding 5-year cumulative incidence BCRL of 25.8%. On multivariate analysis, none of the ALTJ metrics were associated with BCRL risk. Only increasing age, increasing BMI, and increasing number of nodes, were associated with a higher risk of developing BCRL The 6-year LRR rate is 3.2%, axillary recurrence rate is 1.7%, and isolated axillary recurrence rate is 0%. The ALTJ is not validated as a critical OAR for reducing BCRL risk. Until such an OAR is discovered, the axillary PTV should not be modified or dose reduced in efforts to reduce BCRL.

Axillary lymph node recurrence following wire-directed sentinel lymph node dissection for breast cancer patients with biopsy-proven axillary metastases prior to neoadjuvant chemotherapy at a safety net medical center.

Although sentinel lymph node dissection (SLND) after neoadjuvant chemotherapy (NAC) is feasible, axillary management for patients with pretreatment biopsy-proven axillary metastases and who are clinically node-negative after NAC (ycN0) remains unclear. This retrospective study was performed to determine the rate of axillary lymph node recurrence for such patients who had wire-directed (WD) SLND. Patients treated with NAC from 2015 to 2020 had axillary nodes evaluated by pretreatment ultrasound. Core biopsies were done on abnormal nodes, and microclips were placed in nodes during biopsy. For patients with biopsy-proven node metastases who received NAC and were ycN0 by clinical exam, WD SLND was done. Patients with negative nodes on frozen section had WD SLND alone; those with positive nodes had WD SLND plus axillary lymph node dissection (ALND). Of 179 patients receiving NAC, 62 were biopsy-proven node-positive pre-NAC and ycN0 post-NAC. Thirty-five (56%) patients were node-negative on frozen section and had WD SLND alone. Twenty-seven (43%) patients had WD SLND + ALND. Forty-seven patients had postoperative regional node irradiation. With median follow-up of 40 months, there were recurrences in 4 (11%) of 35 patients having WD SLND and 5 (19%) of 27 having WD SLND + ALND, but there was only one axillary lymph node recurrence, identified by CT scan. Axillary node recurrence was very uncommon after WD SLND for patients who had pretreatment biopsy-proven node metastases and were ypN0 after NAC. These patients would be unlikely to derive clinical benefit from the addition of completion ALND to SLND.

Abstract GS4-02: Oncological Outcomes Following Omission of Axillary Lymph Node Dissection in Node Positive Patients Downstaging To Node Negative with Neoadjuvant Chemotherapy: the OPBC-04/EUBREAST-06/OMA study

Abstract Background: Data on the oncologic safety of omission of axillary lymph node dissection (ALND) in node positive (N+) patients who downstage to ypN0 with neoadjuvant chemotherapy (NAC) is sparse. Additionally, there is no consensus on which axillary staging procedure should be used in this setting, sentinel lymph node biopsy (SLNB) alone or in combination with localization and retrieval of the clipped positive node, also known as targeted axillary dissection (TAD). Whether the reduction in the false negative rate observed with TAD translates into a significant reduction in the rate of axillary recurrence is unknown. We sought to evaluate oncologic outcomes after omission of ALND in a large, real-world cohort of breast cancer (BC) patients and to compare rates of axillary recurrence after SLNB with dual tracer mapping vs. TAD. Methods: Data were collected from 19 centers in the Oncoplastic Breast Consortium (OPBC) and EUBREAST networks. Patients with T1-4 biopsy-proven N1-3 BC who underwent NAC followed by axillary staging with either SLNB with dual tracer mapping or TAD and who were pathologically node negative (ypN0) were included. ypN0 was defined as the absence of any tumor or isolated tumor cells. Competing risk analysis was performed to assess the cumulative incidence rates of axillary recurrence, locoregional recurrence, and any invasive (locoregional or distant) recurrence. Two-year cumulative incidence rates were compared between TAD and SLNB using the Gray’s test. Type I error rate was set to 0.05 (α). Results: We included 785 patients (565 treated with SLNB and 220 with TAD) treated with NAC followed by surgery from 01/2014-12/2020. Median patient age was 50 years. The majority (57%) of patients had clinical T2 tumors, and 95% had N1 disease. Most (55%) were HER2+, and 21% were triple negative. Most patients (81%) received anthracycline and taxane-based chemotherapy regimens, but NAC regimens differed between patients treated with TAD and those treated with SLNB (Table 1). All patients with HER2+ tumors received anti HER2 therapy. Nodal radiotherapy was administered to 76% of patients, and was more common in patients who underwent TAD (82% TAD vs 74% SLNB, p=0.017). Breast pathologic complete response (ypT0/is) was more frequent among those patients that had TAD (80% TAD vs. 66% SLNB, p&amp;lt; 0.001). TAD localization was with wire in 46%, radioactive seed in 40%, ultrasound in 5%, tattoo in 2%, and with a combination of these techniques in 7%. The clipped node was successfully retrieved in 94% of TAD cases. The median number of lymph nodes removed was lower in the TAD group compared to the SLNB group [3 (IQR 3-5) vs 4 IQR 3-5), p&amp;lt; 0.001], as was the median number of sentinel lymph nodes [3 (IQR 2-4) vs 4 IQR 3-5), p&amp;lt; 0.001] (Table 1). The 5-year rates of any axillary recurrence, locoregional recurrence, and any invasive recurrence in the entire cohort were 1.1% (95%CI 0.39-2.4%), 3.1% (95%CI 1.6-5.3%) and 10% (95%CI 7.6-13%), respectively. The two-year cumulative incidence of axillary recurrence did not differ between patients treated with TAD compared to SLNB (0% vs 0.9%, p=0.19). Conclusion: Early axillary recurrence after omission of ALND in patients who successfully downstage from N+ to ypN0 with NAC is a rare event following both SLNB or TAD, and was not significantly lower in TAD than SLNB. Although longer follow-up is needed to confirm these findings, the main advantage of TAD seems to be a reduction in the number of lymph nodes removed. Overall, these results support omission of ALND in patients who successfully downstage to node negative disease after NAC. Table 1: Clinicopathological Features of the Study Cohort, Stratified by Axillary Staging Technique Citation Format: Giacomo Montagna, Mary Mrdutt, Astrid Botty, Andrea V. Barrio, Varadan Sevilimedu, Judy C. Boughey, Tanya L. Hoskin, Laura H. Rosenberger, E Shelley Hwang, Abigail Ingham, Bärbel Papassotiropoulos, Bich Doan Nguyen-Sträuli, Christian Kurzeder, Danilo Diaz Aybar, Denise Vorburger, Dieter Michael Matlac, Edvin Ostapenko, Fabian Riedel, Florian Fitzal, Francesco Meani, Franziska Fick, Jacqueline Sagasser, Jörg Heil, Konstantin J. Dedes, Laszlo Romics, Maggie Banys-Paluchowski, Maria Del Rosario Cueva Perez, Marcelo Chavez Diaz, Martin Heidinger, Mathias K. Fehr, Mattea Reinisch, Nadia Maggi, Nicola Rocco, Nina Ditsch, Oreste Davide Gentilini, Regis Resende Paulinelli, Sebastian Sole Zarhi, Sherko Küemmel, Simona Bruzas, Simona Di Lascio, Tamara Parissenti, Uwe Güth, Valentina Ovalle, Christoph Tausch, Monica Morrow, Thorsten Kühn, Walter P. Weber. Oncological Outcomes Following Omission of Axillary Lymph Node Dissection in Node Positive Patients Downstaging To Node Negative with Neoadjuvant Chemotherapy: the OPBC-04/EUBREAST-06/OMA study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS4-02.