Node-positive Breast Cancer Research Articles

Comparing the mutation profiles of primary HER2-positive breast cancers in patients with and without brain metastases.

e13018 Background: Brain metastasis is a frequent and devastating event of HER2-positive breast cancer. Identifying the driver genes of brain metastasis is important for the prevention and treatment of brain metastasis. In this study, we compared the gene mutation profiles of primary breast cancers between patients with and without brain metastases, aiming to identify new candidate genes associated with brain metastases. Methods: HER2-positive and lymph node-positive early breast cancers of 21 patients who eventually developed brain metastases (BM group) and 27 patients without any metastasis (NM group) at a minimum 5-year follow-up were retrieved from the Sun Yat-sen University Cancer Center. Whole-exome sequencing was performed on primary breast cancers (FFPE) and matched normal breast tissues or peripheral blood. Mutect2 was used to detect somatic mutations, and Fisher’s exact test was used to identify genes mutated at different frequencies in the BM and NM groups. The mRNA expression changes of genes mutated at higher frequencies in the BM group were further analyzed in 16-pair matched HER2-positive primary breast cancers and brain metastases using the public dataset (1). Results: The BM and NM groups exhibited similar TP53 (33.3% vs. 55.6%, p=0.15) and PIK3CA (23.8% vs. 25.9%, p=1) mutation rates. The mutation rates of AP3B1 (38.1% vs. 3.7%), DHTKD1 (23.8% vs. 0), ERCC6L2 (38.1% vs. 7.4%), DNAH5 (33.3% vs. 3.7%), ZNF207 (33.3% vs. 7.4%), SPATA31E1 (19.0% vs. 0), FAM111B (19.0% vs. 0), ATG3 (19.0% vs. 0), CDK14 (19.0% vs. 0), TUT4 (19.0% vs. 0), CCNB3 (19.0% vs. 0), MGA (19.0% vs. 0), CLCA1 (28.6% vs. 3.7%), BBS7 (28.5% vs. 3.7%) and GABRG1 (38.1% vs. 11.1%) were significantly (p<0.05) higher in the BM group than in the NM group. Among these genes, CDK14 and TUT4 were significantly downregulated, and ZNF207 and FAM111B were significantly upregulated in brain metastases compared to their matched primary breast cancers. Conclusions: We identified several genes with higher mutation rates in primary breast cancer of patients who eventually developed brain metastases. These genes warrant further investigation in the development of brain metastases in HER2-positive breast cancer. 1. Cosgrove et al. NC 2022.

Updated SEER database study of 21-gene assay to assess breast cancer–specific mortality and benefit of chemotherapy by race and ethnicity.

533 Background: In randomized studies (NSABP B-20, SWOG 8814, TAILORx, RxPONDER), the predictive effect of the 21-gene Breast Recurrence Score assay (RS) on chemotherapy (CT) benefit has been evaluated in patients with node-negative (N0) and node-positive (N+) breast cancer. Retrospective analyses of TAILORx and RxPONDER demonstrated differences in outcome by racial/ethnic groups (RG); however, there were no differences in CT benefit for any of the clinical outcome measures. In this study we characterized the association between the RS result and breast cancer-specific mortality (BCSM) and chemotherapy benefit in BCSM in RG in the recently updated, population-based SEER registries. Methods: Eligible patients were from the SEER 17 registries, November 2022 submission, and had non-metastatic, hormone receptor-positive, HER2-negative, node negative (N0) breast cancer diagnosed between 2006 and 2019 with a RS result. Analyses were weighted using the inverse of estimated propensity of using CT (yes vs. none/unknown). Prognosis was ascertained by estimating breast cancer specific survival (BCSS) at 9 years among patients with CT recorded as none/unknown by RG. The log-rank test was used to compare BCSM by RG. Multivariable Cox models, including RS result (26-100 vs. 0-25) x CT interaction, were used to assess whether RS result was predictive of CT benefit. Analyses were performed in the overall cohort and in Hispanic (H), non-Hispanic Asian and Pacific Islander (NHAPI), non-Hispanic Black (NHB), and non-Hispanic White (NHW) RGs. Results: There were 145,642 eligible patients and 3,212 breast cancer deaths. Median follow-up was 68 months. NHB patients had higher median RS result and CT usage than other groups (p < .001). In N0 patients, higher RS result was associated with lower 9-year BCSS, both overall and by race/ethnicity (p < .001). In Cox multivariable models (Table), the interaction between RS result by CT was significant among all N0 patients (p < .001) and in NHB patients (p = 0.005), NHW patients (p = 0.002), and H patients (p = 0.019), but not in NHAPI patients (p = 0.766). Analyses of patients with N+ disease and more detailed analysis of CT benefit according to RS results by RG are underway and will also be presented. Conclusions: Real-world evidence from the SEER registries in over 145,000 patients confirms the 21-gene assay is prognostic for BCSS in all groups by race and ethnicity. The RS result was predictive of CT benefit in N0 patients overall and in Hispanic, NHB, and NHW patients, but not in NHAPI patients in this analysis. [Table: see text]

Patient-reported outcomes in N1 breast cancer: A phase III trial comparing whole-breast to whole-breast plus regional irradiation after taxane-based chemotherapy (KROG 1701).

577 Background: Recent randomized trials have highlighted the benefits of regional node irradiation (RNI) in high-risk node-positive or pN1 breast cancer, yet its impact in the context of modern taxane-based adjuvant chemotherapy remains unclear. In this multi-center phase III trial, we study to prove the hypothesis that there is no difference in terms of disease-free survival between standard whole-breast irradiation (WBI) with RNI and WBI alone in pN1 breast cancer patients receiving taxane-based adjuvant chemotherapy. Comprehensive patient-reported outcomes (PROs) collected at multiple time points are now reported. Methods: The KROG 17-01 trial (NCT03269981), a prospective, multicenter, non-inferiority study, randomized patients with pN1 breast cancer after breast-conserving surgery and adjuvant taxane-containing chemotherapy to WBI or WBI+RNI. Both conventional and hypofractionated radiotherapy (RT) were allowed. PROs were assessed using the EORTC QLQ-C30 and QLQ-BR23 modules. All data were collected at baseline, during RT, and at follow-up intervals of 3-6 months, 1, 2, 3, 4, and 5 years post-treatment. Linear mixed models were used to compare PROs between treatment arms. Results: From April 2017 to December 2021, 840 patients were enrolled; 777 received intervention as assigned, and 750 completed baseline PRO questionnaires (387 in WBI+RNI, 363 in WBI). Overall, PRO domains improved over time (p<0.001). During RT, the WBI+RNI group experienced more fatigue, nausea, and vomiting (p<0.05), and reported lower global health (p=0.090) and physical functioning (p=0.049) with borderline significance compared to the WBI group. At 3-6 months post-RT, WBI+RNI group also showed higher arm symptom scores (p=0.030). Apart from these specific timepoints, no significant differences were observed in other PRO domain scores, including arm and breast symptoms, between treatment arms. In addition, there was no significant differences in PRO domains according to RT techniques and fractionation, except for breast symptoms during RT, favoring hypofractionation and intensity-modulated RT. Conclusions: In patients with pN1 breast cancer treated with taxane-based adjuvant chemotherapy, adding RNI was associated with minor, transient declines in specific PRO domains. However, these differences were not clinically significant, indicating comparable overall patient experiences between the two treatment arms. Clinical trial information: NCT03269981 .

Clinical and economic benefit of genomic testing strategies to guide the treatment of patients with HR+/HER2- breast cancer in the US.

10584 Background: Multiple testing technologies are available to inform treatment decisions for hormone receptor positive (HR+) and human epidermal growth factor receptor 2 negative (HER2-) early-stage breast cancer, including tumor profiling and germline genetic testing (GGT). The 21-gene assay provides an estimate of distant recurrence risk and potential clinical benefit of chemotherapy. GGT identifies pathogenic variants which inform lifetime cancer risk as well may inform therapy options. This study explored the potential synergy of utilizing both tests by assessing the cost-effectiveness of this strategy compared to no testing from a societal perspective. Methods: A health economic model was developed using best practices to assess a patient cohort with HR+/HER2-, node-negative (N0) or node-positive (N1) breast cancer that was guided to surgical and adjuvant treatment by GGT ( ATM, BRCA1/2, CDH1, CHEK2, PALB2, PTEN,and TP53) and the 21-gene assay. Treatment effectiveness was informed by clinical trials (TAILORx and RxPONDER); costs for treatment, monitoring, and health utilities were sourced from literature. Clinical expert opinion and guidelines informed current US clinical practice. The base case analysis evaluated lifetime total costs, life-years, and quality-adjusted life years (QALYs) versus no testing. Scenario and sensitivity analyses were performed to evaluate model robustness. Results: The testing strategy was dominant (lower cost and higher QALYs gained) compared to no testing leading to a QALY improvement of 0.286 and cost savings of $16,463 in the N0 population (Table) and a 0.099 QALY improvement and $299 cost savings in the N1 population. Scenario analyses indicated that while the 21-gene assay was the primary driver of results, there were synergistic effects when tests were combined. Sensitivity analysis supported cost-effectiveness at most willingness-to-pay thresholds and identified the probability of chemotherapy and rate of distant recurrence as the most impactful model inputs. Conclusions: Using a testing strategy including both the 21-gene assay and GGT enables optimization of treatment decisions in early HR+/HER2- breast cancer, improving patient outcomes at reduced costs. [Table: see text]

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

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

Personalizing Locoregional Therapy in Patients With Breast Cancer in 2024: Tailoring Axillary Surgery, Escalating Lymphatic Surgery, and Implementing Evidence-Based Hypofractionated Radiotherapy.

The management of axillary lymph nodes in breast cancer is continually evolving. Recent data now support omitting axillary lymph node dissection (ALND) in most patients with metastases in up to two sentinel lymph nodes (SLNs) during upfront surgery and those with residual isolated tumor cells after neoadjuvant chemotherapy (NACT). In the upfront surgery setting, ALND is still indicated, however, in patients with clinically node-positive breast cancer or more than two positive SLNs and, after NACT, in case of residual micrometastases and macrometastases. Omission of the sentinel lymph node biopsy (SLNB) can be considered in many postmenopausal patients with small luminal breast cancer, particularly when axillary ultrasound is negative. Several randomized controlled trials (RCTs) are currently aiming at eliminating the remaining indications for ALND and also establishing omission of SLNB in a broader patient population. The movement to deescalate axillary staging is in part because of the association between ALND and lymphedema, which is swelling of an extremity because of lymphatic damage and obstructed lymphatic drainage. To reduce the risk of developing this condition, patients undergoing ALND can undergo reverse mapping of the axilla and immediate reconstruction or bypass of the lymphatics from the involved extremity. Decongestion and compression are the foundation of conservative treatment for established lymphedema, while lymphovenous bypass and lymph node transfer are surgical procedures to address the physiologic dysfunction. Radiotherapy is an essential component of breast locoregional therapy: more than three decades of radiation research has optimized treatment according to patient's risk of local recurrence while substantially reducing the number of treatment visits. High-quality RCTs have shown the efficacy and safety of hypofractionation-more than 2Gy radiation dose per treatment (fraction)-significantly reducing the burden of radiotherapy treatment for many patients with breast cancer. In 2024, guidelines recommend no more than 15-16 fractions for whole-breast and nodal radiotherapy, with some recommending five fractions for whole-breast radiotherapy. In addition, simultaneous integrated boost (SIB) has been shown to be noninferior to sequential boost with regards to ipsilateral breast tumor recurrence with similar or reduced long-term side effects, also reducing overall treatment length. Further RCTs are underway investigating other indications for five fractions, including SIB and regional node irradiation, such that, in future, it may be possible for the majority of breast radiotherapy patients to be treated with a 1-week course. This manuscript serves to outline the latest updates on axillary surgical staging, lymphatic surgery, and evidence-based radiotherapy in the treatment of breast cancer.

Machine Learning Model for Predicting Axillary Lymph Node Metastasis in Clinically Node Positive Breast Cancer Based on Peritumoral Ultrasound Radiomics and SHAP Feature Analysis.

This study seeks to construct a machine learning model that merges clinical characteristics with ultrasound radiomic analysis-encompassing both the intratumoral and peritumoral-to predict the status of axillary lymph nodes in patients with early-stage breast cancer. The study employed retrospective methods, collecting clinical information, ultrasound data, and postoperative pathological results from 321 breast cancer patients (including 224 in the training group and 97 in the validation group). Through correlation analysis, univariate analysis, and Lasso regression analysis, independent risk factors related to axillary lymph node metastasis in breast cancer were identified from conventional ultrasound and immunohistochemical indicators, and a clinical feature model was constructed. Additionally, features were extracted from ultrasound images of the intratumoral and its 1-5 mm peritumoral to establish a radiomics feature formula. Furthermore, by combining clinical features and ultrasound radiomics features, six machine learning models (Logistic Regression, Decision Tree, Support Vector Machine, Extreme Gradient Boosting, Random Forest, and K-Nearest Neighbors) were compared for diagnostic efficacy, and constructing a joint prediction model based on the optimal ML algorithm. The use of Shapley Additive Explanations (SHAP) enhanced the visualization and interpretability of the model during the diagnostic process. Among the 321 breast cancer patients, 121 had axillary lymph node metastasis, and 200 did not. The clinical feature model had an AUC of 0.779 and 0.777 in the training and validation groups, respectively. Radiomics model analysis showed that the model including the Intratumor +3 mm peritumor area had the best diagnostic performance, with AUCs of 0.847 and 0.844 in the training and validation groups, respectively. The joint prediction model based on the XGBoost algorithm reached AUCs of 0.917 and 0.905 in the training and validation groups, respectively. SHAP analysis indicated that the Rad Score had the highest weight in the prediction model, playing a significant role in predicting axillary lymph node metastasis in breast cancer. The predictive model, which integrates clinical features and radiomic characteristics using the XGBoost algorithm, demonstrates significant diagnostic value for axillary lymph node metastasis in breast cancer. This model can provide significant references for preoperative surgical strategy selection and prognosis evaluation for breast cancer patients, helping to reduce postoperative complications and improve long-term survival rates. Additionally, the utilization of SHAP enhancing the global and local interpretability of the model.

Evaluating Magnetic Seed Localization in Targeted Axillary Dissection for Node-Positive Early Breast Cancer Patients Receiving Neoadjuvant Systemic Therapy: A Comprehensive Review and Pooled Analysis.

Background/Objectives: De-escalation of axillary surgery is made possible by advancements in both neoadjuvant systemic therapy (NST) and in localisation technology for breast lesions. Magseed®, developed in 2013 by Dr. Michael Douk of Cambridge, United Kingdom, is a wire-free localisation technology that facilitates the localisation and retrieval of lymph nodes for staging. Targeted axillary dissection (TAD), which entails marked lymph node biopsy (MLNB) and sentinel lymph node biopsy (SLNB), has emerged as the preferred method to assess residual disease in post-NST node-positive patients. This systematic review and pooled analysis evaluate the performance of Magseed® in TAD. Methods: The search was carried out in PubMed and Google Scholar. An assessment of localisation, retrieval rates, concordance between MLNB and SLNB, and pathological complete response (pCR) in clinically node-positive patients post NST was undertaken. Results: Nine studies spanning 494 patients and 497 procedures were identified, with a 100% successful deployment rate, a 94.2% (468/497) [95% confidence interval (CI), 93.7-94.7] localisation rate, a 98.8% (491/497) retrieval rate, and a 68.8% (247/359) [95% CI 65.6-72.0] concordance rate. pCR was observed in 47.9% (220/459) ) [95% CI 43.3-52.6] of cases. Subgroup analysis of studies reporting the pathological status of MLNB and SLNB separately revealed an FNR of 4.2% for MLNB and 17.6% for SLNB (p = 0.0013). Mean duration of implantation was 37 days (range: 0-188). Conclusions: These findings highlight magnetic seed localisation's efficacy in TAD for NST-treated node-positive patients, aiding in accurate axillary pCR identification and safe de-escalation of axillary surgery in excellent responders.

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

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

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

BackgroundLymph 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.MethodsThis 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.ResultsAmong 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 20–49 mm vs. ≥ 50 mm) and breast pCR (OR 0.38, 95% CI 0.15–0.96) were associated with residual LN metastases in the axilla.ConclusionsBreast 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 PO1-03-02: Impact of Body Mass Index (BMI) on the efficacy of different adjuvant chemotherapy schedules in patients with breast cancer: analysis from the randomized phase III GIM2 trial

Abstract Background: The long-term results of the Italian randomized phase III GIM2 study showed that, in women with node-positive breast cancer (BC), dose-dense (DD) chemotherapy significantly improved both disease-free survival (DFS) and overall survival (OS) compared with standard-interval (SI) chemotherapy. Obesity has been identified as an independent poor prognostic factor in patients with BC, with a potential negative impact on the efficacy and toxicity of systemic therapies. Nevertheless, the specific influence of body mass index (BMI) on the efficacy of different adjuvant chemotherapy schedules (DD or SI) remains a subject of debate. This analysis aimed to investigate this hypothesis in patients enrolled in the GIM2 trial. Methods: GIM2 was a randomized multicentric phase III trial that compared different chemotherapy schedule (DD vs SI) and regimen (FEC-P vs EC-P) in 2091 node-positive early breast cancer patients. BMI (kg/m2) was categorized as follows: &amp;lt; 18.5 (underweight), 18.5 to &amp;lt; 25 (lean), 25 to &amp;lt; 30 (overweight), and ≥ 30 (obese). The primary endpoint was to assess association between BMI and DFS and OS. Survival estimates were compared using the Kaplan-Meier method and log-rank test. Univariate and multivariable Cox proportional hazard models, adjusted for relevant prognostic factors, were used. Results: A total of 1925 patients were included in the present analysis, of whom 31.6% (n=632) were overweight and 19.3% (n=386) obese. Median age was 52 years. Overweight-obesity condition was significantly associated with postmenopausal status, greater representation of T2-T4 tumors with N &amp;gt; 2 in both patients in the DD and SI arm. After a median follow-up of 15.0 years (IQR 8.4-16.3), compared to patients with normal BMI, those who were overweight or obese at diagnosis had a higher risk of experiencing a DFS event (Hazard Ratio [HR] 1.11 95% CI 0.94-1.31 and HR 1.37 95%CI 1.14-1.65, respectively, p=0.003) and OS event (HR 1.11 95% CI 0.89-1.38 and HR 1.59 95%CI 1.26-2.01, respectively, p=0.0003). No significant interaction was found between BMI and treatment schedule in terms of DFS (p for interaction=0.56) nor OS (p for interaction=0.19). At the multivariate analysis, in the DD arm, adjusted HR (aHR) for DFS and for OS were 1.01 (95% CI 0.75- 1.35) and 1.04 (95% CI 0.72-1.52) for obese vs. normal BMI groups, and 0.88 (95% CI 0.68- 1.15) and 0.77 (95%CI 0.54-1.10) for overweight vs. normal BMI groups, respectively. In the SI arm, aHRs for DFS and OS were 1.24 (95% CI 0.94- 1.63) and 1.35 (95%CI 0.96- 1.90) for obese vs. normal BMI groups, and 1.04 (95%CI 0.82- 1.33) and 1.01 (95% CI 0.74-1.40) for overweight vs. normal BMI groups, respectively. Similar results were observed when considering hormone receptor-positive and negative BC separately. Conclusion: In the GIM2 trial, BMI was prognostic but not predictive of different benefit to adjuvant chemotherapy. In high-risk patients, DD schedule should be considered the preferred schedule irrespective of BMI. Citation Format: Francesca Poggio, Eva Blondeaux, Marco Tagliamento, Marta Perachino, Simone Nardin, Benedetta Conte, Sabino De Placido, Mario Giuliano, Valeria Forestieri, Michelino De Laurentiis, Adriano Gravina, Giancarlo Bisagni, Anita Rimanti, Anna Turletti, Cecilia Nisticò, Angela Vaccaro, Francesco Cognetti, Alessandra Fabi, Simona Gasparro, Ornella Garrone, Ylenia Urracci, Maria Grazia Alicicco, Mauro Mansutti, Paola Poletti, Pierpaolo Correale, Claudia Bighin, Fabio Puglisi, Filippo Montemurro, Giuseppe Colantuoni, Luca Boni, Matteo Lambertini, Lucia Del Mastro. Impact of Body Mass Index (BMI) on the efficacy of different adjuvant chemotherapy schedules in patients with breast cancer: analysis from the randomized phase III GIM2 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 PO1-03-02.

Abstract PO2-23-06: Clinical study of stained region lymph node biopsy (SrLNB) in axillary surgery after neoadjuvant systemic therapy in patients with axillary lymph node positive breast cancer

Abstract Background The probability of axillary lymph node converting from positive to negative after neoadjuvant systemic therapy (NST) for breast cancer patients is approximately 40%. A variety of axillary lymph node biopsy surgeries based on sentinel lymph node biopsy (SLNB) can help to omit axillary lymph node dissection (ALND). The common disadvantages, however, are mainly the restrictions, such as the need for strict regulation of the use of radiotracers, the high number of retrieved lymph nodes required, and the need to purchase ancillary equipment. The more restrictions there are, the more they limit the spread and availability of the technique and, more importantly, reduce the number of patients who will benefit. In fact, for patients with metastatic lymph nodes, the sentinel lymph nodes must be included in the lymph nodes that have metastasized. If these metastatic lymph nodes can be accurately marked and precisely retrieved after NST, it is possible to assess whether the axillary lymph nodes are converted from positive to negative without the need for SLNB. Materials and methods Breast cancer patients with pathologically confirmed axillary lymph node metastases who were receiving NST were recruited for this study. Before NST, carbon nanoparticles suspension injections were injected into the cortex of the pathologically confirmed metastatic lymph node to stain the region where the metastatic lymph node was located. The lymph nodes in the stained region were retrieved by stained region lymph node biopsy (SrLNB) during the axillary surgery, followed by ALND, without the use of SLNB. Finally, the identification rate and false-negative rate (FNR) of SrLNB were statistically analyzed according to pathology data. Results A total of 159 patients were successfully enrolled in this study between September 24, 2020 and December 2, 2022, with an axillary pCR rate of 40.9% (65/159). The identification rate of SrLNB was 100% (159/159), with an overall FNR of 5.3% (5/94). Subgroup analysis revealed that in the subgroups of 1, 2, 3 and ≥4 SrLN, the FNR was 0%, 0%, 0% and 8.9% (5/56), respectively, whereas in the cN1, cN2 and cN3 subgroups the FNR was 7.7% (3/39), 2.6% (1/38) and 5.9% (1/17), respectively. The FNR indexes were within the safety threshold of 10% in all subgroups. Conclusion SrLNB has a high identification rate and a low FNR and is useful for screening patients with positive to negative axillary lymph nodes for omitting ALND. srLNB requires only the use of an affordable and radiation-free carbon nanoparticles suspension injection for marking, making the whole technique simpler and easier to disseminate. The data from this study also suggest that SLNB may not be mandatory for axillary biopsy in patients with positive axillary lymph nodes undergoing NST. Table 1. General characteristics of enrolled patients. Table 2. Analysis of factors affecting axillary pCR rates. Table 3. Analysis for the FNR of SrLNB. Citation Format: Jue Wang, Rui Chen, Cuiying Li, Hailing Zha, Qiannan Zhu, Lifeng Huang, Xiaoming Zha. Clinical study of stained region lymph node biopsy (SrLNB) in axillary surgery after neoadjuvant systemic therapy in patients with axillary lymph 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 PO2-23-06.

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 PO4-05-12: High expression of SLC9A2 is correlation with lymphatic metastasis and poor survival in breast cancer

Abstract Background: SLC9A2 encodes Na+/H+ exchanger 2 which is an essential solute carrier protein on the surface of multiple cells. The prediction potentials of SLC9A2 in lymphatic metastasis and survival were unknow but explored in this study of breast cancer. Methods: Expression of SLC9A2 was determined in breast cancers (n=127) using real time quantitative polymerase chain reaction. Transcript levels of this gene was analysed in the breast cancers for the implication in lymph node involvement and survival using Mann-Whitney test with SPSS (Version 27). The relation of prognosis was also analysed by Kaplan Meier plotter in breast cancer. Results: In lymph node positive breast cancer, the expression of SLC9A2 shown an increase trend than no metastasis (n=43, median=25.9, interquartile range [IQR] [0.9-215.4] vs. n=44, median=4.9, IQR [0.2-31.8], p=0.1213). SLC9A2 expression in TNM stage Ⅱ was significantly higher than stage Ⅰ (n=31, median=42, IQR [0-195] vs. n=47, median=3.3, IQR [0.2- 31.6], p=0.0267) and also showed in the pathological type of invasive ductal carcinoma (n=27, median=42, IQR [3- 550] vs. n=35, median=3.3, IQR [0.2-31.8], p=0.0223). Kaplan Meier plotter showed over survival of SLC9A2 high expression was significantly worse than SLC9A2 low expression (66 months vs. 123.6 months, Hazard Ratio [HR]=1.57 [1.3-1.9], p=0.000), also found in estrogen receptor (ER) positive (63.8 months vs. 173.7 months, HR=2.19 [1.6-3.01], p=0.000). In patients with tamoxifen therapy, SLC9A2 high expression also had poor survival comparing to low expression (HR=2.86 [1.4-5.86], p=0.0026). Conclusions: High expression of SLC9A2 is correlation with lymph node metastasis and poor survival in breast cancer. SLC9A2 could be as a predictor for lymphatic involvement and survival and might be an indicator for detection of resistance to endocrine therapy. Citation Format: Binbin Cong, Xiaoshan Cao, Wen Jiang, Lin Ye. High expression of SLC9A2 is correlation with lymphatic metastasis and poor survival in 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 PO4-05-12.

Abstract PO3-01-13: A study of the impact of the implementation of the Oncotype Dx 21-gene breast-cancer assay during the SARS-CoV-2 pandemic for 1-3 node positive early breast cancer: The Clatterbridge Cancer Centre Experience

Abstract Background: The 21-gene breast cancer (BC) assay (Oncotype Dx) is used to predict chemotherapy benefit in ER+, HER-2- lymph node (LN) negative BC. The RxPONDER trial demonstrated that post-menopausal patients with ER+, HER2- BC with 1-3 LN and a recurrence score (RS) of &amp;lt; 25 did not benefit from adjuvant chemotherapy. In response to the SARS-CoV-2 pandemic Oncotype Dx was implemented for ER+, HER2- 1-3 LN+ BC patients in Merseyside, UK (population 2.6 million) This study sought to understand the impact of this measure on clinical practice. Methods: All patients whose tumours were assessed with Oncotype Dx assay between Mar 20 - Nov 22 were identified through the Exact Sciences portal. Menopausal status, tumour characteristics, RS and chemotherapy regimen were recorded. The impact on cancer care was estimated using the number of infusions and clinic visits specified by our institution chemotherapy protocol for node positive disease. The financial impact was calculated using the test list price, estimated costs of adjuvant chemotherapy in the UK (Annals of Oncology, Volume 32, suppl 2 S46). The number of patients predicted to receive chemotherapy pre-oncotype DX was calculated using data from the UK PONDx trial data. Results: A total of 242 patients were tested over the 32 month period. Table 1 summarises the clinico-pathological characteristics including by RS score. The median age was 58.5 and 77.3% (n=187) were post-menopausal. The median tumour size was 25mm and median LNs with macrometastasis was 1. 198 (81.9%) patients had an RS &amp;lt; 25. Overall 73 patients (30%) received chemotherapy of which 34 had an RS &amp;lt; 25. Pre-menopausal patients were more likely to receive chemotherapy with RS &amp;lt; 25 than post-menopausal patients, 47.9% (23/48) vs 7.3% (11/150) respectively. In the absence of Oncotype Dx testing 169 patients would have received adjuvant chemotherapy. Therefore, 96 patients avoided chemotherapy. This equates to 1,620 chemotherapy infusions and 324 clinic attendances. The estimated cost saving was ~£50K. Conclusions: This real-world study demonstrates that the use of Oncotype DX assay for ER+,HER2- 1-3 LN+ early BC spared a significant number of patients chemotherapy during the SARS-CoV-2 pandemic, so avoiding the risk of adverse effects. This also resulted in benefits to the healthcare system with a reduction in scheduled cancer care and achieved financial savings. This, therefore, demonstrates the benefit of using the Oncotype Dx assay. Table 1: Clinico-pathological information Citation Format: Alexandra Johnson, Sonia Bathla, Leena Chagla, Joanne Cliff, Allison Hall, Anita Hargreaves, Clare Hart, Zafar Malik, Chandeena Roshanlall, Raj Sripadam, Carlo Palmieri, Helen Innes. A study of the impact of the implementation of the Oncotype Dx 21-gene breast-cancer assay during the SARS-CoV-2 pandemic for 1-3 node positive early breast cancer: The Clatterbridge Cancer Centre Experience [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 PO3-01-13.

Abstract PO3-23-07: Evaluation of the role of axillary ultrasound to estimate axillary nodal burden to guide de-escalation of upfront axillary surgery in node positive early breast cancer patients

Abstract Background: Axillary surgery is now routinely de-escalated in clinically node negative breast cancer patients with limited axillary nodal burden (up to 2 involved sentinel nodes) based on the results of ACOSOG-Z0011 and AMAROS trials. However, patients with proven axillary metastasis following on ultrasound (AUS) guided core needle biopsy (CNB), undergoing primary surgery are still subjected to an axillary lymph node dissection (ALND) irrespective of the magnitude of the axillary nodal burden. If we could predict axillary nodal burden with a low false negative rate (FNR) for the presence of extensive axillary nodal involvement, we can then hypothesize that axillary surgery could be safely de-escalated in this cohort of patients. We investigated whether pre-operative AUS suggesting limited axillary burden is sensitive enough to rule out gross axillary disease burden. Methods: A single institution retrospective study. We undertook an electronic chart review of all T1 to T3 patients undergoing upfront ALND with either mastectomy or breast conserving surgery between January 2019 and June 2023. Patients with palpable axillary nodes, locally advanced breast cancer or a completion ALND after positive sentinel lymph node biopsy (SLNB) were excluded from the study. Clinical and pathological characteristics associated with nodal burden of disease were evaluated. Limited axillary burden was defined as &amp;lt; 2 involved nodes with ≥3 taken as gross nodal burden for primary analyses. Sensitivity analyses were carried out with limited axillary burden defined as &amp;lt; 3 involved nodes (N1) and ≥4 (N2) taken as gross nodal burden. Subgroup analyses in T1 or T2 tumors were carried out as well. The probabilities of discordant events, defined as limited burden on AUS-CNB but gross burden on final histopathology evaluation (HPE), assuming 10% FNR, were estimated using inverse cumulative binomial distribution function. Results: Data on the exact number of suspicious nodes on AUS were missing for 2 patients, therefore, the final study cohort included 39 patients. The correlation between AUS nodal burden and that on HPE was moderate (Spearman’s rho = 0.48; p = 0.0018). The sensitivity and specificity of AUS in identifying gross nodal burden were 61% and 81% respectively. Observation of 9 discordant events in 22 patients with low burden on AUS ruled out an FNR of &amp;lt; 10% with 99.99% certainty. The sensitivity and specificity in T1/T2 subgroup were 60% and 75% respectively. The sensitivity analyses classifying N1 as limited and N2 as gross axillary burden showed the sensitivity and specificity of 35% and 82% respectively and an FNR of &amp;lt; 10% was ruled out with 99.996% certainty. Conclusion: Pre-operative AUS alone lacks the sensitivity and specificity to accurately predict the true axillary nodal burden to safely guide de-escalation of axillary surgery. AUS followed by targeted axillary dissection (TAD) in conjunction with a dual technique SLNB may provide the desired sensitivity and specificity to guide de-escalation of axillary surgery. A prospective evaluation of this approach is merited. Given the limited number of patients that could be enrolled in such prospective study from individual institutions, an international collaborative effort is needed to address this important research question. Citation Format: Nidhi Garg, Mangesh Thorat, Hisham Hamed, Ashutosh Kothari. Evaluation of the role of axillary ultrasound to estimate axillary nodal burden to guide de-escalation of upfront axillary surgery in node positive early breast cancer 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 PO3-23-07.

Abstract PO5-22-12: Development and Validation of a Genomic Test to Predict Tumor Response of the Axillary Nodes after Neoadjuvant Chemotherapy (NAC) in Patients with HER2-negative Breast Cancer: Results of the AGO-35 trial

Abstract Background: De-escalation of axillary surgery in patients with lymph node-positive breast cancer is currently being tested in ongoing trials for patients with downstaged nodes after neoadjuvant chemotherapy (NAC). A proportion of such patients will achieve an excellent axillary node response to NAC, i.e. conversion to pathologic node-negative status after chemotherapy. Genomic prediction of tumor chemosensitivity before final surgery may identify which patients could safely undergo conservative surgical management of their regional lymph nodes. Methods: The AGO-35 (NCT0203274) is a prospective trial for patients with HER2 negative breast cancer scheduled for neoadjuvant chemotherapy that includes an anthracycline- based regimen followed by 3-4 cycles of taxanes. The LN predictor is a newly developed model for predicting the probability of pathological lymph node-positivity after NAC in triple-negative (TNBC) or hormone-receptor positive (HR+) breast cancer. To calculate the LN predictor, which is developed in microarray, we calibrated the normalized individual gene module and SET ER/PR from RNAseq to the Affymetrix U133A platform using independently combined total of 220 pairs of TNBC samples with both RNAseq and U133A microarray results. The logistic regression model is applied for the prediction of the binary outcome, pathological lymph node-positive or negative after NAC. The cut-points of LN predictor in TNBC and HR+ samples were pre-determined for each subtype of breast cancer and then, independent, blinded evaluation in the AGO-35 trial samples. Results: A total of 251 patients with HER2 negative breast treated with neoadjuvant chemotherapy were included. The LN predictor was validated on 189 qualified samples with wtRNA sequence. Statistical analysis of 181 samples is shown in Table 1. Conclusion: Preliminary results of the AGO-35 trial show that the newly developed molecular LN predictor may accurately predict chemosensitivity response to NAC, in high proportion of patients with TNBC. Supported by: Wissenschaftsfonds (FWF) KLI 406 EUBREAST study group AGO Österreich Breast Cancer Research Foundation (BCRF-0158) Table 1. Genomic prediction of chemosensitivity Citation Format: Florentia Peintinger, Thorsten Kühn, Hans-Christian Kolberg, Roland Reitsamer, Sabine Schmatloch, Elisa Sieghartsleitner, Lili Du, Andrea Berghold, W. Fraser Symmans. Development and Validation of a Genomic Test to Predict Tumor Response of the Axillary Nodes after Neoadjuvant Chemotherapy (NAC) in Patients with HER2-negative Breast Cancer: Results of the AGO-35 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 PO5-22-12.

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 PO2-02-03: Clinical and pathological factors associated with Oncotype DX® 21-Gene recurrence score in patients diagnosed with early stage breast cancer in a low-middle income country

Abstract INTRODUCTION: Oncotype DX® recurrence score (ODX RS) is a 21-gene assay warranted to determine the the prognosis in patients with hormone receptor positive, HER-2 negative early stage breast cancer. In this context, the test is also predictive of benefit of adjuvant chemotherapy.1,2,3 OBJECTIVES: We aimed to correlate the clinical and pathological factors associated with Oncotype DX® 21-Gene in patients diagnosed with early stage Breast Cancer. Additionally, description of adjuvant treatment patterns and survival outcomes were described according to the Oncotype DX® 21-Gene result. METHODS: Data from medical records from a single center in Brazil were collected retrospectively from women over 18 years diagnosed with early breast cancer between 2012 and 2022. Included patients were diagnosed with stage T1-T2 breast cancer, hormone receptor positive, HER-2 negative, with up to three positive lymph nodes. All included patients had an Oncotype DX® test performed after definitive breast surgery. The ODX RS has been categorized into two levels according to menopausal status. Correlation between breast cancer recurrence and clinicopathological characteristics was done. The software SPSS was used for statistical analyzes with the significance of 0.05. RESULTS: From 197 patients, 20 have had breast cancer recurrence (10.15%) whom 10 were premenopausal and 10 were postmenopausal. The median ODX RS in these 20 patients was 15 (ranged from 9 to 31). The most common site of recurrence was breast and regional recurrence in 18 patients (90%). Adjuvant chemotherapy was omitted in 16 patients (80%) who have had breast cancer recurrence. Among premenopausal patients whose ODX RS was &amp;gt;20, 33 patients (91.66%) received adjuvant chemotherapy. Among postmenopausal patients whose ODX RS was &amp;gt;25, 19 (86.36%) received adjuvant chemotherapy. The probability of recurrence free survival was worse in premenopausal patients &amp;gt; 44-years-old compared to those with &amp;lt; =44 years-old (p = 0.036) and also worse in histological grade 3 tumors compared to grade 1 (p=0.0048). Tumor size &amp;gt;14 millimeters (mm) was correlated to worse recurrence free survival in premenopausal patients (p=0.017). Low estrogen and progesterone receptor was associated with a higher ODX RS (p=0.0035 and p&amp;lt; 0.0001, respectively) in premenopausal patients, but not associated with recurrence free survival. Clinicopathological characteristics and recurrence free survival correlation in postmenopausal patients were not significant. CONCLUSION: This retrospective analysis suggests that factors other than the Oncotype DX® score, such as age and grade contributed to worse survival outcomes among our patients population. Of note, age older than 44 years-old, histological grade 3 and tumor size &amp;gt;14 mm were associated with a higher probability of recurrence in premenopausal patients, despite the Oncotype DX® score. REFERENCES: 1. Paik S, Shak S, Tang G, Kim C, Baker J, Cronin M, et al. A multigene assay to predict recurrence of tamoxifen-treated, node-negative breast cancer. N Engl J Med [Internet]. 2004;351(27):2817–26. Available from: http://dx.doi.org/10.1056/NEJMoa041588. 2. Sparano JA, Gray RJ, Makower DF, Pritchard KI, Albain KS, Hayes DF, et al. Adjuvant chemotherapy guided by a 21-gene expression assay in breast cancer. N Engl J Med [Internet]. 2018;379(2):111–21. Available from: http://dx.doi.org/10.1056/NEJMoa1804710. 3. Kalinsky K, Barlow WE, Gralow JR, Meric-Bernstam F, Albain KS, Hayes DF, et al. 21-gene assay to inform chemotherapy benefit in node-positive breast cancer. N Engl J Med [Internet]. 2021;385(25):2336–47. Available from: http://dx.doi.org/10.1056/NEJMoa2108873. Table 1 – Clinical and pathological characteristics of 197 hormone receptor positive, HER-2 negative early breast cancer patients who did the Oncotype DX® 21-Gene Recurrence Score assay. Data from medical records collected retrospectively of women diagnosed with early breast cancer between 2012 and 2022 from a single center in Brazil. Figure 1 – Probability of recurrence free survival in premenopausal patients according to age &amp;lt;=44 (blue line) or &amp;gt; 44-years-old (pink line). Data from medical records collected retrospectively of women with hormone receptor positive, HER-2 negative early breast cancer who did the Oncotype DX® 21-gene assay diagnosed between 2012 and 2022 from a single center in Brazil. Figure 2 – Probability of recurrence free survival in premenopausal patients according to histological grade. Tumor with histological grade 1 (blue line) or histological grade 3 (pink line). Data from medical records collected retrospectively of women with hormone receptor positive, HER-2 negative early breast cancer who did the Oncotype DX® 21-gene assay diagnosed between 2012 and 2022 from a single center in Brazil. Citation Format: Carolina Cavalcanti Gonçalves Ferreira, Julio Araujo, Shermann Brandão Rodrigues Moreira, Antônio Buzaid, Débora Gagliato. Clinical and pathological factors associated with Oncotype DX® 21-Gene recurrence score in patients diagnosed with early stage breast cancer in a low-middle income country [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-02-03.

Abstract PO1-23-01: A novel nomogram for predicting the possibility of omitting axillary lymph node dissection after neoadjuvant chemotherapy for clinical node-positive breast cancer

Abstract Purpose: Currently, there is no validated strategy established for omitting axillary lymph node dissection (ALND), when axillary node metastases are expected to disappear with neoadjuvant chemotherapy (NAC) for clinical node-positive (cN+) breast cancers. In contrast, it was reported that the axillary pathological complete response (pCR) rate to NAC for cN+ breast cancer is approximately 40%. Therefore, it is necessary to develop a more accurate method for predicting nodal pCR (ypN0) to select patients who can omit ALND after NAC for cN+ breast cancer. Methods: This is a single-centered, retrospective clinical study conducted in 128 patients with cN+ primary breast cancer who underwent ALND after NAC between January 2014 and July 2021 at Saitama Medical Center. Clinical complete response (cCR) was defined as the disappearance of the primary tumor or axillary node metastasis, as confirmed by the findings of imaging. The pCR was defined as the absence of microscopic evidence of residual invasive carcinoma in primary breast tumor or axillary nodes. Clinicopathological variables were compared using Fisher’s exact test or logistic regression, as appropriate. Statistical significance was set at p&amp;lt; 0.05. Results: The median age of the patients was 52 years; 48.4% were premenopausal, 38.3% had cT3 or higher, 22.7% had cN2 or higher, and 50% had stage III disease. Estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) positivity accounted for the patients were 58.6%, 50%, and 31.3%, respectively. NAC included sequential taxanes and anthracyclines in 47.7% of the patients, and anti-HER2 therapy was used in all patients of HER2-positive breast cancer. Breast primary tumor cCR (ypT0) was 29.7% and ypN0 was 44.5%. The ypN0 rate was 19.5% higher than the ypT0 rate in all patients (p &amp;lt; 0.001); it was 4.8% higher in the luminal subtype (p=0.009), 25.5% higher in the triple-negative subtype (p &amp;lt; 0.001), and 29.3% higher in the HER2 subtype (p=0.015). Additionally, the ypN0 rate was 3.9% higher than the axillary node cCR (ycN0) rate in all patients (p &amp;lt; 0.001), 7.6% lower in luminal type (p &amp;lt; 0.001), 13.6% higher in triple-negative type (p &amp;lt; 0.001), and 5% higher in the HER2 subtype (p=0.006). When ycN0 was predicted to be ypN0, the negative predictive value (NPV) was 77.2% and the false negative rate (FNR) was 19.7% (Table 1). In the association between ypN0 and preoperative clinico-pathological factors in cN+ breast cancer treated with NAC, univariate analysis showed significant differences in ER negativity (ER-) [hazard ratio (HR): 0.186, 95% confidence interval (CI): 0.086–0.401, p&amp;lt; 0.001], PgR negativity (HR: 0.360, 95% CI: 0.176–0.736, p=0.005), HER2 positivity (HER2+) (HR: 4.394, 95% CI: 1.941–9.949, p&amp;lt; 0.001), ycT0 (HR: 10.667, 95% CI: 4.020–28.304, p&amp;lt; 0.001), and ycN0 (HR: 9.966, 95% CI: 4.399–922.576, p&amp;lt; 0.001). The multivariate analysis revealed that ER, ycT0, and ycN0 were independent predictive factors for ypN0 after NAC in the patients with cN+ breast cancer (Table 2). These independent factors in multivariate analysis were used to create a nomogram for ypN0 prediction. The points added were 82 if the patient was ER-, 56 if the patient was ycT0, and 100 if the patient was ycN0, and the total of these scores was used to predict whether the patient had ypN0. When the Receiver Operating Characteristic curve was used to determine the cut-off value of the total points, 119 or more points were predicted to be ypN0, the NPV was 92.9%, and the FNR was 4.5%, which demonstrated an approximately 15% improvement over the prediction of ypN0 by ycN0 alone (Table 3). Conclusion: ER, ycT0, and ycN0 are independent predictive factors of ypN0 in cN+ breast cancer, suggesting that ypN0 prediction using a nomogram may contribute to individualized axillary treatment. Table 1. Accuracy of ypN0 prediction with ycN0 after NAC for clinical node-positive breast cancer Table2. Univariate and multivariate analyses of the relationship between preoperative clinicopathological factors and pathologically axillary node-negative after neoadjuvant chemotherapy in clinical node-positive breast cancer Table 3. Accuracy of ypN0 prediction after NAC for clinical node-positive breast cancer using Nomogram Citation Format: Hirohito Seki, Yuki Ishiguro, Ken Shimizu, Akitsugu Makino, Yoshiharu Ishizaka, Ai Tsuchiya, Hirotsugu Isaka, Shigeru Imoto. A novel nomogram for predicting the possibility of omitting axillary lymph node dissection after neoadjuvant chemotherapy for clinical 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 PO1-23-01.