Recurrent Breast Research Articles

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

Abstract ABSTRACT Background Individualized treatment strategies are highlighted for breast cancer patients in the last decades. Therefore aggressive surgical approaches have begun to evolve towards minimally invasive tailored interventions. SLNB is widely used in patients who received neoadjuvant treatment (NAC) and axillary lymph node dissection (ALND) is recommended for patients with axillary residual disease after NAC. In our study, we investigated regional recurrence rates in patients with limited axillary residual disease after NAC who underwent imaging-guided (MR+USG) axillary surgery plus radiotherapy (RT) instead of ALND. Materials and Methods 139 patients whose clinical stages were T1-3 and N1 at the time of diagnosis, who had a clinically good or complete axillary response after neoadjuvant therapy, and who had axillary residue (≤3 pathological lymph nodes) with favorable response to NAC (>50% fibrotic changes) in the final pathological examination were included in the study. The tumor stage and the number of pathological lymph nodes were assessed by USG, MMG, MR, and PET-CT examination (The minimum number of lymph nodes to be removed was determined according to imaging findings). All patients underwent imaging-guided SLNB (blue dye) and imaging-guided palpable lymph node excision. The patients were re-evaluated with their final pathology results in the multidisciplinary councils for suitable further treatments, ALND or RT. Peripheral lymphatic radiotherapy was applied to patients whose radiology and pathology results were compatible and no further surgery was done. The patients whose radiologically detected number of positive nodes was inconsistent with the number of metastases in pathology examination and who were presumed to have the gross residual disease underwent ALND. These patients were excluded from the study. Results The median age was 47 years. The median number of lymph nodes excised was 4. The total number of excised lymph nodes was between 1-3 in 64 (46%) patients and between 4-6 in 62 (45%) patients. 13 (9%) patients had ≥7 lymph nodes. 1 metastatic lymph node was found in all patients with 1 positive lymph node according to imaging findings. Of 41 patients with 2 radiologically positive lymph nodes, 1 metastatic lymph node was found in 17 (41%) patients, 2 metastatic lymph nodes in 22 (53%), and 3 metastatic lymph nodes in 2 (5%) patients respectively. Radiology reported 3 positive lymph nodes in 22 patients, of which 1 metastatic lymph node was found in 8 (36%), 2 metastatic lymph nodes in 10 (45%), and 3 metastatic lymph nodes in 4 (18%). The median follow-up period was 44 months. One patient had breast recurrence at the 31st month and one patient had lymphatic recurrence in the supraclavicular area at the 39th month. Systemic recurrence was noted in 6 (4.3%) patients. No axillary recurrence occurred during the follow-up period. Conclusions Patients with pathological-suspicious ≤ 3 lymph nodes shown by imaging (USG, MR, and PET-CT) who responded to NAC but still have residual disease in the axilla can be safely treated with SLNB(blue dye)+imaging-guided axillary approach and adjuvant RT. This approach eliminates the need for ALND in patients with low-volume residual axillary disease. Table. Patient characteristics Citation Format: Mahmut Muslumanoglu, Baran Mollavelioglu, Selman Emiroglu, Hasan Karanlik, Mustafa Tukenmez, Kamuran Ibis, Aysel Bayram, Ravza Yılmaz, Neslihan Cabıoğlu, Abdullah Igci. Imaging tailored axillary approach combined with radiotherapy eliminates axillary lymph node dissection in low-volume axillary disease after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-23-01.

Abstract GS03-01: Magnetic Resonance Imaging and a 12-Gene Expression Assay to Optimize Local Therapy for Ductal Carcinoma In Situ: 5-year clinical outcomes of E4112

Abstract BACKGROUND. Advanced diagnostics such as magnetic resonance imaging (MRI) and gene-expression profiles are potentially useful to guide treatment in patients with ductal carcinoma in situ (DCIS). To evaluate these tests, we performed a prospective single arm multicenter study. We have previously reported the impact of MRI on surgical management of DCIS patients, and the effect of a 12-gene DCIS Score (DS) on radiotherapy (RT) use after wide local excision (WLE). We now report a pre-planned analysis of ipsilateral breast events (IBE) at 5-years. METHODS. Adult women with a core needle biopsy diagnosis of DCIS and eligible for WLE based on conventional imaging were registered following consent. All registered patients underwent breast MRI. Those still eligible, and willing, to receive WLE after appropriate follow-up biopsies underwent resection to free margins. DCIS sections were submitted to Exact Sciences for DS. Those with a low DS (< 39) were advised to omit RT; those with intermediate/high (inter/hi) DS (≥39) were advised to receive RT. All participants were monitored at 6-month intervals for any breast cancer event, and for survival. An IBE was defined as the first DCIS or invasive recurrence in the ipsilateral breast following the final WLE. Participants without IBE were censored by date of last contact or date of death for those who died. Follow-up was truncated at 5 years from WLE. Using data available as of 07-06-2023, Kaplan-Meier (K-M) curves were constructed to estimate the time-to-event distributions for subjects who received RT and for those who did not. The 5-year IBE rates and 95% confidence intervals (CIs) were estimated from K-M curves for all subjects with a DS (analogue of Intention to Treat [ITT] analysis), and for the subset who were compliant with their DS-based RT recommendation (Per Protocol analysis). The analyses were repeated for subgroups based on age at DCIS diagnosis (< 50 vs. ≥ 50). RESULTS. Of 339 women evaluable for the previously reported primary analysis (PMID 30653209), 171 (50.4%) underwent WLE with free surgical margins and had DS available for RT recommendations (ITT population). Of these, 7/82 low DS patients underwent RT, and 5/89 inter/hi DS patients declined RT; thus, the adherence to DS-based RT recommendations was 93%. At a median of 5 years of follow-up from final WLE, the ITT population experienced a total of eight IBE events (4.8%, 95% CI 2.4, 9.4) with 5-year IBE rates that were similar for participants with a low DS and for those with a inter/hi DS: 5.1% (95% CI: 1.9, 12.9) and 4.5% (95% CI 1.7, 11.7), respectively. Stratification by age did not alter these results: among women aged < 50 years (n=33), the IBE rate was 6.7% (95% CI 1.0, 38.7) for low DS and 5.6% (95% CI 0.8, 33.4) for inter/hi DS. Among women aged ≥ 50 years (n=138), the IBE rate was 4.7% (95% CI 1.5, 13.8) for low DS and 4.3% (95% CI 1.4, 12.7) for inter/hi DS. In the per-protocol analysis (N=159 adherent to RT recommendations), IBE rates were also similar for participants who had a low DS and no RT [5.5% (95% CI 2.1, 14.1)] and for those with inter/hi DS who received RT [4.8% (95% CI: 1.8% to 12.3%)]. Again, there was no discernible influence by age as categorized above. CONCLUSION. We report the first prospective data on use of DCIS Score for RT decisions, and 5-year IBE rates. We find that DS-based recommendations are followed by >90% of patients. Although the sample size is limited, the data are reassuring in that the IBE rate is similar between the low DS group treated with WLE alone and the inter/hi DS group treated with WLE and radiation, whereas prior studies have shown a marked difference in IBE rates by DS with excision alone. Therefore, this prospective trial provides strong evidence to support the omission of RT after surgery in DCIS patients with low DS, and its use in patients with intermediate/high DS. Citation Format: Seema Khan, Justin Romanoff, Constantine Gatsonis, Habib Rahbar, Ruth Carlos, Sunil Badve, Jean Wright, Constance Lehman, Worta McCaskill-Stevens, Ralph Corsetti, Derrick Spell, Kenneth Blankstein, Linda Han, Jennifer Sabol, John Bumberry, Ilana Gareen, Bradley Snyder, Lynne Wagner, Kathy Miller, Joseph Sparano, Christopher Comstock. Magnetic Resonance Imaging and a 12-Gene Expression Assay to Optimize Local Therapy for Ductal Carcinoma In Situ: 5-year clinical outcomes of E4112 [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 GS03-01.

Abstract PO5-09-04: Oncotype DX Breast Recurrence Score® analysis in early-stage breast cancer associated with CHEK2, ATM and PALB2 germline pathogenic variants

Abstract Background: The 21-gene assay (Oncotype DX Recurrence Score, RS) is the only clinically validated assay to determine the prognosis in hormone-positive, HER2-negative breast cancer (BC) patients treated with endocrine therapy alone by predicting locoregional and distant recurrence. Outcomes of Oncotype RS in BRCA-associated BC has been studied previously, but the results of RS analysis in BC patients with the other BC susceptibility genes have not been documented. This study evaluates the clinical and pathological characteristics of BC patients with ATM, CHEK2 and PALB2 germline pathogenic variants (PV). Methods: Patients with invasive hormone-positive, HER2-negative BC who have had Oncotype DX Breast Recurrence Score® testing and who underwent genetic testing in the Breast Medical Oncology and the Breast Clinical Cancer Genetics Clinic at the University of Texas MD Anderson Cancer Center (MDACC) were identified from the prospectively maintained research database. Clinical and tumor characteristics were analyzed using descriptive statistics. Results: Between 1996 and June 2023, 5652 patients with Oncotype RS were included in this analysis. Amongst those 828 BC patients had genetic testing and 81 patients were found to have a pathogenic variant: 17 patients with a CHEK2 mutation, 10 patients with an ATM mutation, and 18 patients with a PALB2 mutation. Among patients with CHEK2 PV, median Oncotype RS was 17 (5–32) overall, 21 (13–32) for patients age < 50, and 14.5 (5–28) for patients age ≥50 (p= 0.2). Among patients with ATM PV, median RS was 16.5 (3–54) overall, 25 (10–54) for patients age < 50, and 14.5 (3–29) for patients age ≥50 (p= 0.19). Among patients with PALB2 PV, median RS was 26.5 (15–40) overall, 20 (15–40) for patients age < 50, and 31 (26–37) for patients age ≥50 (p= 0.012). Further patient and tumor characteristics are shown in Table 1. Conclusion: This is a single-institutional cohort of hormone-positive, HER2-negative BC patients who had Oncotype RS and who underwent genetic testing. Further analysis on clinical and tumor pathological characteristics and long-term outcome is ongoing. Table1. Patient and tumor characteristics Citation Format: Fatma Akkoc Mustafayev, Angelica Gutierrez Barrera, Diane Liu, Banu Arun. Oncotype DX Breast Recurrence Score® analysis in early-stage breast cancer associated with CHEK2, ATM and PALB2 germline pathogenic variants [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 PO5-09-04.

Abstract PO1-01-10: Comparison of the cost-effectiveness of multigene assays for HR+/HER2- node-negative early-stage breast cancer in the US

Abstract Background Traditional clinico-pathologic features, such as tumor grade and size, age, and menopausal status, may provide incomplete prognostic information, and have limited ability to predict chemotherapy benefit for patients with hormone-receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2)-, axillary lymph node-negative (N0) early-stage breast cancer, leading to both under- and over-treatment with adjuvant chemotherapy. Multigene expression profile tests have been used in clinical practice to complement clinico-pathologic information to optimize treatment decisions. To date, the Oncotype DX Breast Recurrence ScoreÒ test is the only multigene assay with the ability to predict chemotherapy benefit validated by evidence from randomized clinical trials and supported by NCCN and ASCO guidelines. Other commercially available assays in the US include MammaPrintÒ, EndoPredictÒ and Prosigna RORÒ, which offer prognostic information beyond traditional clinico-pathologic features to improve treatment decisions. The relative cost-effectiveness of the four multigene assays compared to using clinico-pathologic risk alone to guide chemotherapy decisions was assessed from a societal perspective in the US. Methods A cost-effectiveness model built in Microsoft Excel estimated the cost-effectiveness of the Oncotype DXÒ test, MammaPrint, EndoPredict and Prosigna ROR compared to using clinical-pathological risk alone over a lifetime horizon. The model structure consisted of a decision-tree portion informed using published studies for the distribution of distant recurrence risk categories as defined by each test (low, intermediate, and high risk for the Oncotype DX test and Prosigna ROR, low and high risk for MammaPrint and EndoPredict). Decision impact studies and clinical expert opinion informed the proportion of patients allocated to adjuvant chemotherapy conditional on test result category. A Markov discrete health state model then simulated the future risk of distant recurrence, and long-term adverse effects of chemotherapy: acute myeloid leukemia (AML), and congestive heart failure (CHF), and aggregated the costs and outcomes of treatment decisions over a patient’s lifetime. The probability of distant recurrence of breast cancer conditional on test result category was derived from the most up-to-date studies assessing the performance of tests: TAILORx for the Oncotype DX test, MINDACT for MammaPrint, and TransATAC for EndoPredict and Prosigna ROR. Costs were estimated from a US societal perspective in 2020 US dollars (including Medicare healthcare costs, lost productivity and patient out-of-pocket chemotherapy costs from literature), and outcomes were expressed in terms of life-years, quality-adjusted life-years (QALYs), and net monetary benefit (NMB). The cost-effectiveness of each multigene assay compared to using clinico-pathologic risk alone was presented using the incremental cost-effectiveness ratio (ICER). Results Using the Oncotype DX test resulted in the largest lifetime cost savings (-$13,395) and generated the largest QALY gain (0.25) out of the four multigene assays included in the model, when compared to using clinico-pathologic risk alone (Table 1). All four multigene assays represented a cost-effective use of resources from a societal perspective (based on the accepted willingness-to-pay threshold of $100,000 per QALY gained), with a low net lifetime cost or net cost savings with positive QALY gain. Conclusion These results support the use of multigene assays to guide treatment decisions in node-negative HR+/HER2- early-stage breast cancer to improve treatment outcomes, and also result in substantial net cost savings from a societal perspective. The prediction of chemotherapy benefit using the Oncotype DX test resulted in substantially higher cost savings and improved breast cancer outcomes. Citation Format: Vladislav Berdunov, Gebra Cuyun Carter, Christy Russell, Sara Campbell, Jennifer Racz, Yara Abdou. Comparison of the cost-effectiveness of multigene assays for HR+/HER2- node-negative early-stage breast cancer in the US [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 PO1-01-10.

Abstract PO5-15-11: A Novel Biosignature to Predict Radiation Therapy Response in Early-Stage Invasive Breast Cancer Treated with Breast-Conserving Surgery

Abstract Introduction: Radiation therapy (RT) is a standard component of treatment for most patients with early-stage, hormone receptor-positive, invasive breast cancer (BC) following breast-conserving surgery (BCS). RT recommendations are primarily based on clinicopathologic (CP) factors, such as tumor size, nodal status, and histological grade. While these factors provide prognostic information, their ability to accurately identify patients at a higher risk of ipsilateral breast recurrence (IBR) or those who will significantly benefit from RT is unclear. Therefore, incorporation of additional predictive markers beyond CP factors is warranted and there remains a need to refine the selection criteria for patients who will derive the greatest benefit from RT. In this study, we aimed to explore the role of immune and metabolic signaling axes as potential predictive markers for RT response in hormone receptor-positive breast cancer patients. Methods: A cohort of 939 women from Sweden were diagnosed with BC between 1987 and 2004. A subset of 471 patients was diagnosed with T1-T2N0M0 BC and underwent BCS with negative margins. Patients were treated with BCS plus/minus RT (median dose 50Gy) based upon physician preference. Biomarkers were assayed in formalin-fixed paraffin-embedded tissue micro arrays using multiplex immunofluorescence and multi-spectral imaging in a CLIA lab (Laguna Hills, CA). Immune and metabolic axes were defined employing biomarkers and used to classify patients into three risk groups: 1) Low Risk (lower baseline risk and no RT benefit), 2) Elevated Risk (higher baseline risk and significant RT benefit), and 3) Residual Risk (higher baseline risk and suboptimal RT benefit). Risk groups were analyzed for IBR rate using Kaplan-Meier and Cox proportional hazards analyses. Risk group prognosis and RT prediction was assessed for RT-risk group interaction in multivariable analysis, adjusting for CP factors. Results: Among the patients with complete biomarker data, 261 were hormone receptor-positive, and had a median follow-up of 140 months. Median age was 62 years (28-88 years), and median tumor size was 1.1 cm (0.1-4 cm). Some patients (21%) received endocrine therapy (ET), and most (76%) received RT, with 79% of patients who received ET also receiving RT. In the overall population, RT following BCS was associated with a reduction in HR for recurrence (HR=0.3, 95%CI [0.1, 0.5], p< 0.001). Patients classified as Low Risk (41%) did not have a significant benefit from RT (HR=0.9, 95%CI [0.1, 8.3], p=0.95) in multivariable analysis adjusted for CP factors. For patients who were classified as Elevated Risk (31%), multivariable analysis showed a higher IBR rate without RT (HR=5.7, 95%CI [1.3, 25.1], p< 0.021) relative to the Low Risk group who had a significant benefit from RT (HR=0.1, 95%CI [0.02, 0.2], p< 0.001). Patients classified into the Residual Risk group (28%) had no significant reduction from RT (HR=0.7, 95%CI [0.2, 2.0], p=0.61). However, in multivariable analysis adjusted for CP factors, patients treated with RT in the Residual Risk group had higher IBR rates (HR=3.7, 95%CI [1.6, 8.7], p=0.0026) compared to RT-treated patients in other risk groups. The biosignature was predictive for RT benefit in multivariable analysis adjusted for CP factors (p-interaction < 0.001). Conclusions:The biosignature used in this study demonstrated the potential to identify patients who may derive limited benefit from RT, allowing for tailored therapeutic approaches. These findings underscore the importance of individualized treatment decisions based on risk stratification. Further clinical validation and refinement of risk stratification strategies are warranted to optimize outcomes in hormone receptor-positive, BC patients undergoing BCS. Citation Format: Troy Bremer, Karuna Mittal, Chirag Shah, Frank Vicini, Steven Shivers, Charlotta Wadsten. A Novel Biosignature to Predict Radiation Therapy Response in Early-Stage Invasive Breast Cancer Treated with Breast-Conserving Surgery [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 PO5-15-11.

Abstract PO2-22-03: Reirradiation for locally recurrent breast cancer: a long-term single centre experience

Abstract Background: About 10–15% of patients with breast cancer will eventually develop an ipsilateral breast recurrence. The management of cancer relapse in previously irradiated tissues is a challenging therapeutic issue, and data on breast re-irradiation are currently lacking. Hence, the aim of this work was to report our experience with breast re-irradiation for non-metastatic recurrent breast cancer. Material and Methods: All patients who underwent a breast or chest wall re-irradiation in the Institut Curie, Paris, France between 2003 and 2019 were identified. Those who underwent re-irradiation only in other volumes than the ipsilateral breast were excluded. Local recurrence-free (LRFS), overall survival (OS), disease-specific survival (DSS), progression-free survival (PFS), and metastasis-free survival (MFS) were evaluated. Physician-reported acute and late toxicities were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) 5.0. Results: Between 2003 and 2019, 21.372 patients underwent a breast irradiation in our institution. Of these, 453 received a new irradiation to the controlateral breast and/or lymph nodes, 105 to the homolateral lymph nodes without breast/chest wall re-irradiation and 28 received a second course of radiotherapy (RT) to the homolateral breast. These 28 patients were included in this study. Median follow up after re-irradiation was 45.5 months (IQR 33.5-79.75 months). The median age at the time of second breast RT was 63 years (IQR, 49-78). The median RT dose to the breast/chest wall was 60 Gy (interquartile range (IQR) 50-66 Gy) for the first irradiation and 48 Gy (IQR 30-50 Gy) for the second. The median cumulative dose was 100 Gy (IQR 92-114 Gy). The median time between the two courses of RT was 47 months (IQR 22.75-109.5 months). Eighteen (64%) patients were treated with a curative intent and 10 (36%) for palliative purposes. Ten (36%) had a macroscopic breast residue at re-irradiation. The second RT course was performed with electrons, photons and a combination of both in 13 (46%), 8 (29%) and 6 (21%) patients, respectively. At 2 years, LRFS, OS, DSS, PFS and MFS were respectively 59%, 79%, 82%, 50% and 75% in the whole cohort. 2-year-LRFS (72% vs 31%, p=0.02), OS (94% vs 50%, p< 0.01), DSS (94% vs 56%, p< 0.01) and PFS (61% vs 20%, p=0.02) differed significantly between patients treated in a curative or in a palliative intent, but not MFS (78% vs 69%, p=0.77). Among patients, 8 (29%) remained relapse-free 5 years after the second course of RT. Only one patient experienced an acute grade 3 adverse event (dermatitis), and 1 presented a late grade 3 one (skin fibrosis). One patient with major cardiovascular risk factors died of myocardial infarction 13 months after the second left breast irradiation. Conclusion: Breast or chest wall re-irradiation appears to be feasible with good disease control in patients treated with a curative intent, and acceptable toxicity rates. In addition, a significant number of patients were disease-free 5 years after the second course of RT. Prospective larger data with longer follow-up are needed to confirm these findings. Citation Format: Jérémy Baude, Rémi Dendale, Alain Fourquet, Youlia Kirova. Reirradiation for locally recurrent breast cancer: a long-term single 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 PO2-22-03.

Abstract PO1-07-01: Artificial intelligence-based prediction of Oncotype DX Score from whole slide images using human-interpretable features and breast biomarkers

Abstract Background The Oncotype DX Breast Recurrence Score assay (ODX) is a commonly used genomic test for patients with estrogen receptor (ER)-positive, HER2-negative, early-stage invasive breast cancer. While ODX predicts patients’ recurrence risk and benefit from chemotherapy, it is tissue and time-consuming, and expensive. Previous deep-learning or non-linear ODX prediction models achieved promising performance using whole-slide images (WSI) or with other covariates (e.g., ER, progesterone receptor (PR), HER-2, Ki-67 scores and tumor stage) but systematic quantification of the contribution of individual histological features to the ODX score remained challenging. Here, we extracted a rich set of human-interpretable features (HIFs) quantifying nuclear morphology and the distribution of cells and tissues in the tumor microenvironment. We used these HIFs, along with manually assessed ER, PR, HER-2 scores, and tumor stage, to predict ODX scores. We also explored the role of Ki-67 features in augmenting our model predictions Methods We developed machine learning models to extract cell, tissue, and nuclear HIFs from WSI stained with hematoxylin and eosin (H&E) and immunohistochemistry (IHC) against Ki-67. These models were deployed on 353 H&E WSI to extract 276 HIFs quantifying cell densities, tissue areas, relative cell counts, and nuclei size, shape and color. Hierarchical agglomerative clustering was applied to cluster these features into 11 groups. Univariate regression was performed to identify correlations between ODX scores and feature clusters. To predict ODX score using HIFs, a multivariable regression model was fitted to the data where regressors are representative features from each cluster, in addition to ER, PR, HER-2 scores and stage as covariates. The model was fitted on the training set (N=266 slides) and evaluated on the held-out test set (N=87 slides). To examine the utility of Ki-67 IHC features in ODX prediction, a Ki-67 model was deployed on a subset of 194 matched Ki-67 IHC WSI to extract count proportions and densities of Ki-67 positive cells in cancer epithelium and stroma. Results Significant positive correlations were identified between ODX scores and feature clusters corresponding to cancer cell density (p < 10-7), macrophage density (p < 10-4), immune cell density (p < 10-16), and variations in cancer nuclear size (p < 10-5) and color (p < 10-3). Significant negative correlations were observed between ODX scores and clusters related to fibroblast density (p < 10-3), and variations of non-cancer cell nuclear color (p = 0.02). Evaluation of our model’s ability to predict ODX scores revealed an association between predicted and observed scores (Pearson r = 0.74). The AUROC for model predictions of high/low classifications (with reference to a cutoff ODX score of 20) was 0.80. Ki-67 features were clustered together with H&E cancer cell density features and showed a stronger correlation with ODX scores compared to the H&E features alone. Combining Ki-67 cell density features with H&E features led to increased performance of the multivariable regression model on the test set compared to H&E features only (r = 0.62 vs. r = 0.59). However, a model combining Ki-67, H&E and covariates performed similarly to a model with H&E and covariates (r = 0.73), suggesting that Ki-67 features may not be needed for ODX prediction when H&E and covariate information is available. Conclusions Our model predicts ODX recurrence scores with comparable performance to other black-box approaches using WSI and breast biomarker status and without the need for, Ki-67 features. Using readily available information, our model has the potential to be a convenient screening tool for patient stratification, which may lead to better patient care, lower costs, and faster treatment. Citation Format: Nhat Le, John Van Arnam, Christian Kirkup, Ylaine Gerardin, Michael Drage, Neha Khaitan, Anurag Sharma, Georgi Galev, Nicholas Indorf, Emily Sansevere, Ilan Wapinski, Stephanie Hennek, Gloria Zhang. Artificial intelligence-based prediction of Oncotype DX Score from whole slide images using human-interpretable features and breast biomarkers [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 PO1-07-01.

Abstract PO4-08-04: Comparison of Outcomes and Prognosis between BRCA Pathogenic Variant Carriers Undergoing Breast-Conserving Surgery versus Mastectomy for Breast Cancer

Abstract Introduction: While outcomes are similar following breast-conserving surgery (BCS) or mastectomy among patients with sporadic breast cancer, data are still controversial for germline BRCA pathogenic variant carriers. We previously compared outcome following BCS between BRCA pathogenic variant carriers and non-carriers, and reported higher ipsilateral breast recurrence and comparable prognosis in the carriers. The purpose of this current study was to compare outcomes among BRCA pathogenic variant carriers undergoing BCS versus mastectomy in long-term follow-up period. Methods: Women with a BRCA pathogenic variant and a stage 0-III breast cancer who underwent definitive surgery from 1987–2021 were retrospectively identified from institutional database. Factors including clinicopathologic information and treatment characteristics were identified. Subsequent local recurrence, regional recurrence, distant recurrence, contralateral breast cancer (CBC), breast cancer-specific survival (BCSS), and overall survival (OS) rates were compared between BCS and mastectomy using Kaplan-Meier method and log-rank test. The chi-square test and t-test were used to compare patient characteristics between the two groups. Results: A total of 232 BRCA mutation carriers with 257 cancers including 25 patients with synchronous bilateral breast cancer were identified. Surgical treatment included BCS for 82 cancers and mastectomy for 175 cancers including nipple-sparing mastectomy for 51 cancers. Patient age at surgery and cancer stage did not statistically differ between BCS and mastectomy groups. Comparing to patients choosing mastectomy, patients who underwent BCS were less likely to be aware of their genetic status before surgery and were more likely to receive radiation therapy (p < 0.001). Contralateral risk reducing mastectomy was performed in 22.5% (18/80) in the BCS group and 48.7% (74/152) in the mastectomy group (p < 0.001) concurrently or at any time after the first definitive surgery. Risk reducing salpingo-oophorectomy was performed in 40% (32/80) in the BCS group and 49% (75/152) in the mastectomy group (p = 0.17). At 7.5 years median follow-up, local recurrence rate was statistically higher in the BCS group than in the mastectomy group (20.0% in BSC vs. 4.6% in mastectomy, p = 0.043). In patients who underwent nipple-sparing mastectomy, 4.0% (2/51) had local subcutaneous recurrence and no nipple-areolar recurrence was observed. Median duration from the first definitive surgery to ipsilateral local recurrence was 10.0 years in the BCS group and 2.3 years in the mastectomy group. Regional lymph node recurrence (11.2% in BCS vs. 6.4% in mastectomy, p = 0.62), distant recurrence (13.7% vs. 9.2%, p = 0.84), CBC (15.0% vs. 8.6%, p = 0.70), BCSS (88.8% vs. 94.1%, p = 0.65) and OS (87.5% vs. 94.1%, p = 0.49) rates did not statistically differ between two groups. Conclusions: With 7.5 years median follow-up, higher local recurrence rate was observed in BCS than in mastectomy among BRCA pathogenic variant carriers. Our results found no statistical difference between BCS and mastectomy in regional recurrence, distant recurrence, CBC, and prognosis, indicating relatively higher risk in BCS. While BCS could be an option for BRCA pathogenic variant carriers willing to continue high-risk breast surveillance, shared decision making should be carefully performed based on the long-term local recurrence risk. Citation Format: Kumiko Kida, Junko Takei, Misato Suzuki, Megumi Okawa, Sakurako Kazama, Sakiko Kondo, Michiko Yamanaka, Atsushi Yoshida. Comparison of Outcomes and Prognosis between BRCA Pathogenic Variant Carriers Undergoing Breast-Conserving Surgery versus Mastectomy for 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 PO4-08-04.

Abstract PO1-22-09: Current margin assessment practice for breast-conserving surgery in China: a single institution audit

Abstract Background The appropriate negative margin width following breast-conserving surgery (BCS) for both ductal carcinoma in situ (DCIS) and invasive carcinoma (IC) has witnessed a shift towards de-escalation in international guidelines. However, there are limited nationwide data regarding margin assessment practice for BCS in China. This study aims to clarify the current real-world status of margin assessment from a single institution audit and secondarily to update the evidence on the association between margin width and local recurrence. Methods Eligible cases were derived from an extensive series of consecutive unselected patients with early invasive breast cancer who were treated with BCS at the Department of Breast Surgery in Shanghai Cancer Center Fudan University (FUSCC) between January 2015 and December 2017. Patient demographic and clinicopathological information as well as follow-up data were extracted from the hospital's electronic medical records. Pathological evaluation of negative margins was defined as no ink on tumor for IC in accordance with the SSO/ASTRO consensus guidelines released in 2014. Where applicable, margins were categorized as tumor on ink (involved), close margins (no tumor on ink but ≤1 mm), clear margins (1-2 mm), wide margins (2-5 mm), and wider margins (>5 mm). The positive margin rate (PMR), reoperation rate, and ipsilateral breast recurrence (IBR) rate were calculated according to different margin widths. Multivariable analyses of factors associated with re-excision were performed using binary logistic regression. Kaplan‒Meier survival curve analysis was performed for local recurrence-free survival (LRFS). Results A total of 2707 patients were enrolled in the current study, with a total PMR of 2.7%. The distribution of margin width revealed that wider margins (>5 mm) were optimized by most surgical oncologists (2092/2707, 77.3%) for BCS in our center. Additionally, the reoperation rates were 1.9% in the whole population, accounting for 48.3%, 7.5%, 4.2%, 0.8%, and 0.4% in each margin group. Specifically, among 247 patients with margins ≤2 mm, 41 (16.6%) received reoperation either by margin re-excision or mastectomy. Multivariable analyses identified that lobular histology, no selective additional resection and in situ pathology of involved/close margins are independent factors of re-excision recommendation. With a median follow-up of 54.3 months, the incidence of IBR was 1.7% in the whole cohort, representing for 5.2%, 4.2%, 2.8%, 1.9%, and 1.3% in each margin group, respectively. Kaplan‒Meier survival curve analysis showed a marginally significant difference in 5-year LRFS between groups with margins >2 mm and margins ≤2 mm (95.9% vs 97.8%, Table 1). Conclusions A wider margin width was preferably adopted in the routine practice of BCS. Our audit was aligned with previous evidence that a minimum clear margin of 2 mm is associated with a lower reoperation rate but favorable local control. Patients with margins no more than 2 mm were more likely to have re-excision in cases of lobular histology, no selective additional resection, and in situ pathology of involved/close margins. Ipsilateral breast recurrence models by margin status Citation Format: Feilin Qu, Cheng-Jia Shen, Wen-Tao Yang, Jun-Jie Li, Guangyu Liu, Zhi-Ming Shao. Current margin assessment practice for breast-conserving surgery in China: a single institution audit [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 PO1-22-09.

Abstract PO5-01-10: Evaluating a computer-aided platform for predicting recurrence and survival in an Oncotype Dx tested breast cancer cohort

Abstract Background: Oncotype DX Breast Recurrence ScoreÒ (ODXRS) is a widely used predictive measure of breast cancer recurrence risk and chemotherapy benefit for patients with estrogen receptor positive (ER+), human epidermal growth factor receptor-2 negative (HER2-) breast cancers. ODXRS testing incurs additional costs and delays. These drawbacks could be obviated by innovative computer-aided technologies within digital pathology workflows. Such technologies could be developed to perform a wide variety of diagnostic and prognostic tests on digital whole slide images (WSIs) of hematoxylin and eosin (H&E)-stained tissue alone. This would save time, cost, and sample tissue whilst still providing critical prognostic information for patient management. Q-Plasia OncoReader Breast (QPORB) is a computer-aided solution which extracts information from H&E WSIs to provide diagnostic and prognostic information for breast cancer specimens. Aims: The aim of this study was to identify whether the computer aided QPROB platform could successfully predict breast cancer recurrence from H&E WSIs alone in line with recurrence predicted by ODXRS. Methods: H&E slides corresponding to tissue blocks sent for ODXRS testing from primary breast cancer resection/excision specimens from St James’s University Hospital, Leeds, UK (n=137 cases, 1 slide per case) were collected, anonymized, and scanned at x20 magnification on an Aperio AT2 scanner. Relevant pathological and clinical data were collected from electronic pathology reports and patient records. These data included ODXRS and recurrence events. QPORB analyzed each case/slide and generated a digital biomarker profile from the H&E images alone, combining statistical physics and tumor biology to quantify malignant cell cycle deformation. QPORB’s biomarker profile and ODXRS for each case was compared to disease-free survival (DFS) and overall survival (OS). Kaplan-Meier survival analyses were performed. Confounding factors (age, tumor grade, invasive tumor size and Charlson Comorbidity Index) were accounted for. Results: Results of three QPORB-generated indices - two putatively associated with overall cell cycle signature and one with G1 deformation, and their combined overall biomarker profile did not predict DFS in this cohort. However, with regards to OS, all three indices and the combined biomarker profile predicted OS over a median follow-up period of 5 years (P=0.044). 5% of WSIs (7/137) did not meet the criteria to be analyzed by QPORB and 4% (6/137) could not be analyzed by QPORB (attrition). While ODXRS similarly predicted OS but not DFS, the follow-up duration was suboptimal. Conclusion: While QPORB indices evaluated in this work, putatively associated with overall cell cycle signature and G1 deformation, did not predict breast cancer recurrence on a par with ODXRS, it has shown promising results as potential adjunct device to provide an estimate of OS for breast cancer patients eligible for ODXRS testing. Future work will expand on this observational cohort, blindly validate these findings, and extend the work to encompass all breast cancer molecular subtypes. Citation Format: Satabhisa Mukhopadhyay, Elizabeth Walsh, Rebecca Millican-Slater, Andrew Hanby, Joanne Stephenson, Tathagata Dasgupta, Nicolas Orsi. Evaluating a computer-aided platform for predicting recurrence and survival in an Oncotype Dx tested breast cancer cohort [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 PO5-01-10.

Abstract PO1-19-01: NRG-BR008: A Phase III Randomized Trial of Radiotherapy Optimization for Low-risk HER2-positive Breast Cancer (HERO)

Abstract Background: Breast radiotherapy (RT) is the standard of care for patients with early-stage breast cancer (BC) who undergo breast-conserving surgery (BCS). However, the magnitude of benefit of RT is less clear in BCS patients with low-risk disease who receive effective systemic therapy. Among patients with early-stage HER2-positive (HER2+) BC, 10-year locoregional recurrence has been reported as low as 1.5% following BCS, adjuvant chemotherapy and HER2-targeted therapy, and RT. Given these exceedingly favorable outcomes, with the addition of HER2-directed therapy, we seek to evaluate the feasibility of omitting RT among patients with early-stage HER2+ BC following BCS and appropriate systemic therapy. Methods: This is a phase III randomized trial for patients ≥40 years with early-stage, node-negative HER2+ (IHC/FISH) BC treated with BCS with negative margins and sentinel lymph node biopsy or axillary dissection. Patients undergoing primary surgery must have pathologic T1 (< 2 cm) N0 disease, while patients receiving neoadjuvant therapy must have clinical T1-2 (with radiographically T< 3.0 cm) N0 disease and exhibit a pathologic complete response (ypT0N0) at surgery. All patients must receive cytotoxic chemotherapy and HER2-targeted therapy, either in the adjuvant or neoadjuvant setting. Stratification is by age (< 60; ≥60), tumor size (≤1 cm; >1 cm), estrogen-receptor status (positive; negative), and systemic therapy sequencing (adjuvant vs neoadjuvant). Patients will be randomized to standard breast RT in addition to continuation of trastuzumab to complete a year of treatment (Arm 1), or trastuzumab alone (Arm 2). Endocrine therapy will be recommended for patients with hormone-receptor positive tumors. The primary endpoint is the recurrence-free interval (RFI). Secondary endpoints include the time to ipsilateral breast recurrence, locoregional recurrence, disease-free survival, and overall survival, in addition to the 7-year ipsilateral breast recurrence rate among those not receiving RT. A health-related quality of life sub-study will assess differences in patient-reported breast pain and worry. We estimate a 7-year RFI of 97.5% with RT and allow for a clinically acceptable decrement of 3.63% without RT (7-year RFI of 93.87%; HR 2.5) to establish omission of RT as non-inferior. NRG-BR008 aims to enroll 1,300 patients over 4.5 years, yielding 80% power to detect the non-inferiority of RT omission with a one-sided α=0.05. We expect to observe the required 38 RFI events within 6 years of additional follow-up. The NRG-BR008/HERO trial opened to accrual in March, 2023. NCT05705401. Support: U10CA180868, -180822, UG1CA189867, U24CA196067; Susan G. Komen Foundation (JR) Citation Format: Lior Braunstein, Melissa Mitchell, Hanna Bandos, William Sikov, Atif Khan, Peter Chen, Patricia Ganz, Reshma Jagsi, Julia White, Reena Cecchini, Hyejoo Kang, Shannon Puhalla, Kelly Bolton, Eileen Connolly, Erica Stringer-Reasor, Kimberly Gergelis, Thomas Julian, Eleftherios Mamounas, Norman Wolmark. NRG-BR008: A Phase III Randomized Trial of Radiotherapy Optimization for Low-risk HER2-positive Breast Cancer (HERO) [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 PO1-19-01.

Abstract PO5-23-05: The Impact of Bi-Annual Diagnostic Imaging on Detecting Ipsilateral Breast Recurrence in Patients Undergoing Breast Conserving Surgery for Breast Cancer

Abstract Introduction: Breast conserving surgery (BCS) represents the preferred option for surgical treatment for a majority of patients with early-stage breast cancer who are eligible for this approach. When compared with mastectomy approaches, BCS provides patients with equivalent survival while preserving the affected breast. It is necessary to achieve clear surgical margins as positive lumpectomy margins are associated with an increased risk for ipsilateral breast tumor recurrence. With advances in imaging techniques, as well as effective systemic therapy and contemporary radiation therapy, local recurrence after BCS has decreased and overall survival for patients has improved. Retrospective studies have quantified the recurrence rate in unifocal breast cancer as 8 - 15% at 20 years. The NCCN recommends annual mammography at least 6 months after post-lumpectomy radiation therapy, but there is little data regarding more frequent surveillance after lumpectomy in the early post-operative setting. The purpose of this study was to evaluate the impact of short interval surveillance mammography on the detection of early in-breast recurrence in patients undergoing BCS. Methods: Our IRB-approved Breast Cancer Database was queried for patients enrolled from 11/2009 to 6/2023 who underwent breast conservation surgery for a diagnosis of in situ or invasive breast cancer in this retrospective analysis. Per our institutional protocol, patients were recommended to undergo diagnostic mammography of the treated breast(s) every 6 months for 2 years after BCS. After the initial 2 year period, bilateral mammography was performed annually in the absence of other indications. Additional supplemental imaging such as breast ultrasound and MRI were performed at physician discretion and based on patient risk and breast density. Variables of interest included the presence of pathogenic germline mutations, family history of breast cancer, and disease characteristics. Our primary endpoint was ipsilateral breast tumor recurrence. Results: Of 2491 patients who underwent breast conservation surgery for in situ or invasive breast cancer, 191 (7.7%) developed recurrent disease, including ipsilateral and contralateral recurrence, and distant disease, in the study period. A total of 83 (3.2%) patients developed ipsilateral breast recurrence during the entire study period. Of those, 19 (22.9%) were detected within the first two years after surgery. Six of the 19 patients (31.6%) had their recurrences detected on yearly diagnostic mammography while 6 (31.6%) patients had their recurrences detected on interval 6-month unilateral diagnostic imaging. In both groups, 5/6 recurrences were invasive disease after an original diagnosis of invasive cancer, and the remaining patient had recurrent DCIS. The remaining 7/19 patients (36.8%) had their ipsilateral recurrences detected on palpation or other diagnostic imaging. In this group as well, there was one case of recurrent DCIS, with the remaining 6 cases representing recurrent invasive cancer. Of the 19 patients with ipsilateral recurrences, none had pathogenic germline mutations. 4 of the 19 patients (21%) had positive margins after their initial lumpectomy surgery with re- excisions required to achieve clear margins. Conclusion: Interval diagnostic surveillance imaging every 6 months after breast conserving surgery identified almost one-third of the ipsilateral breast tumor recurrences that occurred within the first 2 years after surgery in our population. While our numbers are small, the relationship of re-excision lumpectomy surgery to subsequent risk for local recurrence has been described by others, and bears further study. Particularly in view of our observation that the majority of in-breast recurrences were invasive, our data supports the practice of more frequent imaging follow up in the first 2 years after breast conserving surgery. Citation Format: Pabel Miah, Laura Fiedler, Anthony Baez, Athanasios Sevdalis, Alyssa Marmer, Charles DiMaggio, Linda Pak, Richard Shapiro, Karen Hiotis, Deborah Axelrod, Amber Guth, Freya Schnabel. The Impact of Bi-Annual Diagnostic Imaging on Detecting Ipsilateral Breast Recurrence in Patients Undergoing Breast Conserving Surgery for 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 PO5-23-05.

Abstract PO4-08-09: Concordance analysis of paired breast cancer core needle biopsies and surgical excision samples using the Oncotype DX Breast Recurrence Score® assay

Abstract INTRODUCTION: The Oncotype DX Breast Recurrence Score® (RS) assay is validated to predict risk of distant recurrence at 10 years and the benefit of adjuvant chemotherapy in patients with estrogen receptor (ER)+, HER2- early breast cancer who receive 5 years of endocrine therapy. The feasibility of Oncotype DX® testing with diagnostic core needle biopsies (CNB) was demonstrated through analysis of a large commercial laboratory experience. The neoadjuvant ADAPT study showed the clinical utility of deriving the Recurrence Score® (RS) result from CNB as well. However, data are limited on concordance of RS results from paired CNB and surgical samples. Our primary objective was to determine the degree of concordance of RS results between paired tissue samples from the same primary breast tumor of patients with early stage, ER+, HER2- invasive breast cancer who had a CNB and subsequent surgical excision (SE; lumpectomy or mastectomy) without intervening systemic therapy. METHODS: Patients with a commercial RS result on either CNB or subsequent SE were identified through medical record and clinical database review. A pathologist reviewed archival tissue samples to confirm eligibility and selected the other paired CNB or SE block most representative of the tumor tissue for subsequent study Oncotype DX testing. Descriptive statistics were used to summarize patient and tumor characteristics. Wilcoxon signed rank, McNemar’s and Cochran-Mantel-Haenszel tests were used to compare RS between SE and CNB paired samples. Cohen’s Kappa and 95% confidence intervals (CIs) were used to compare the agreement of categorical RS (0-25 and 26-100) result between SE and CNB paired samples. Lin’s concordance correlation and 95% CIs were used to compare agreement of continuous RS between paired samples. RESULTS: A total of 134 patients were identified with paired CNB and SE samples with a median time of 34 (range 5-103) days between collections. Of the 134 patients, a commercial RS result was available for 25 (18.7%) with CNB and 109 (81.3%) with SE. A study RS result was then generated on the other paired sample. Median age was 62 years (range 33-99; 23 patients [17%] were age ≤50 vs. 111 [83%] age >50). Cases were predominantly node negative (107/134 node negative vs. 26/134 node positive; 1/134 unknown) invasive ductal carcinomas (104/134 ductal vs. 18/134 classic lobular vs. 12/134 other). Mean RS results were 15.6 (range 0-56) and 16.6 (range 0-59) for CNB and SE, respectively (p = 0.003), with no statistically significant differences in RS category defined as low vs. high risk (119/134 CNB vs. 114/134 SE for RS 0-25 and 15/134 CNB vs 20/134 SE for RS 26-100; p = 0.13) or low vs. intermediate vs. high risk (85/134 CNB vs. 78/134 SE for RS 0-17 and 43/134 CNB vs. 48/134 SE for RS 18-30 and 6/134 CNB vs. 8/134 SE for RS 31-100; p = 0.19). No differences were observed based on age relative to 50 years or nodal status (data not shown). Cohen’s Kappa statistic k = 0.64 (95% CI, 0.44-0.83) supports substantial agreement between the CNB and SE samples. Lin’s concordance correlation coefficient (CCC) demonstrates similar agreement for the continuous RS result between paired samples (CCC = 0.86 [0.80-0.90]). Overall percent agreement was 91.8% (87.1-96.4%). CONCLUSIONS: Studies evaluating the level of concordance of ER, progesterone receptor, and HER2 biomarker status between CNB and SE samples have found high concordance rates, albeit varied. We now provide data demonstrating high concordance of RS results between CNB and SE specimens obtained from the same breast primary tumor without intervening systemic therapy. This supports use of either biopsy source for testing with a genomic predictor to identify those patients who will most likely benefit from chemotherapy and which patients may be spared. Citation Format: Aziza Nassar, Jodi Carter, Paige Innis, Satish Seerapu, Christy Russell, Helena Hanna, Abigail Lochala, Minetta Liu. Concordance analysis of paired breast cancer core needle biopsies and surgical excision samples using the Oncotype DX Breast Recurrence Score® assay [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 PO4-08-09.

Abstract PO1-14-05: A comparison of chemotherapy recommendations by NPI, Predict, and Oncotype DX testing in UK women with early node positive breast cancer

Abstract Introduction: Gene expression testing is expensive and, unless it changes the chemotherapy (CT) decision, unnecessary. Both Nottingham Prognostic Index (NPI) and Predict Breast Cancer (Predict) are free to use and based on clinico-pathological data. Each gives a guide to the prognosis. Many clinical teams in the UK have used these indices to guide treatment and more recently to help decide who should have access to gene expression testing. NPI scores of ≤2.4 have a cancer-specific ten-year survival of 96%, and >2.4 to ≤3.4, >3.4 to ≤5.4 and >5.4 have survivals of 93%, 78% and 44% respectively. UK oncologists use it as a guide in recommending adjuvant treatment. CT is not recommended for patients with NPI ≤3.4, is discussed as on option for NPI >3.4 to ≤5.4 and is recommended for NPI >5.4. Similarly, Predict can be used to guide CT decisions as follows: < 3% benefit, CT not recommended; 3-5% CT discussed as a possible option; >5% CT recommended. The OncotypeDX® Breast Recurrence Score® test has been assessed recently in the RxPONDER trial which concluded that postmenopausal women with a Recurrence Score (RS) result < 26 showed no benefit from the addition of CT. This study compares the clinical utility of three indices (NPI, Predict, and RS result) by assessing the distribution of NPI and Predict across RS result, evaluates changes in CT recommendations based on risk group, and by estimating the likelihood of CT recommendation. Methods: We recently conducted a prospective UK decision impact, decision conflict and economic analysis of Oncotype DX® test in early node positive, hormone receptor positive and HER2 negative breast cancer involving 664 women. Using these data, we calculated the NPI and the Predict score. Descriptive statistics, logistic regression and McNemar’s tests were used to assess the associations between NPI, Predict, RS result and change in CT decisions for all patients (n=664) and in the cohort of post-menopausal patients recruited after RxPONDER reported (n=176). Results: Table 1 shows similar stratification for all three indices within the low-risk groups, but not for the high-risk groups. Similar results were observed in the post-menopausal, post-RxPONDER cohort. The results of the CT decision change in the post-menopausal, post-RxPONDER patients by NPI and Predict demonstrate the utility of RS results across all NPI and Predict risk groups (Table 2). There was a stronger association between RS result (26-100 vs 0-25) and CT recommendation (OR152.8, 95% CI 53.9-433.2, p< 0.001) as compared to the association between either NPI or Predict (OR 8.7, 95% CI 3.8-19.8, p< 0.001 and OR 7.2, 95% CI 2.8-18.3, p=0.003 respectively), suggesting that UK Oncologists are predominantly using RS to guide their CT decisions. Conclusions: Either basing CT decisions or selecting which patients should undergo OncotypeDX testing by pre-screening with either NPI or Predict risks misclassifing many patients who either need potentially lifesaving CT or who can safely avoid chemotherapy altogether. Table 1. Predict and NPI risk groups by RS result for all patients and for the post-menopausal, post-RxPONDER cohort. Table 2. CT recommendation pre-and post-assay by risk group for post-menopausal, post-RxPONDER patients. Citation Format: Simon Holt, Paige Innis, Priyadharshini Sai-Giridhar, Satish Seerapu. A comparison of chemotherapy recommendations by NPI, Predict, and Oncotype DX testing in UK women with early 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 PO1-14-05.

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.

1418: Feasibility of second conservative treatment with interstitial brachytherapy for breast recurrence

1418: Feasibility of second conservative treatment with interstitial brachytherapy for breast recurrence

Metastasis of serous ovarian carcinoma to the breast: a case report and review of the literature

BackgroundBreast metastasis from primary ovarian cancer is rare, with an estimated frequency of 0.07%. More than 110 cases are reported in the literature of metastatic spread of ovarian cancer to the breast and axilla. This entity usually represents aggressive late disease characterized by multi-drug chemoresistance and a poor prognosis with a median survival time of 16 months. Currently no standardized treatment protocol exists for this condition.Case presentationWe present a case of a 59-year-old Caucasian female with recurrent high-grade serous ovarian cancer who was diagnosed with symptomatic unilateral breast metastasis while on fourth line chemotherapy with weekly paclitaxel. She was treated with local radiation with 2300 cGy to the right breast with a complete response. She then had a subsequent recurrence in the ipsilateral breast 8 months after completion of post treatment imaging. She remains alive to date approximately 2 years after her initial diagnosis of breast metastasis on seventh line treatment.ConclusionsBreast metastasis from primary ovarian cancer is rare and represents advanced disease characterized by multi-drug chemoresistance and a poor prognosis. This case describes radiation therapy as a safe, effective treatment option to improve local control and quality of life in these patients, but with limited durability of response.

Abstract 7339: Mayo Clinic breast cancer cohort: A valuable resource for breast cancer research

Abstract The Mayo Clinic Breast Disease Registry (MCBDR) was developed to serve as a cohort of newly diagnosed breast cancer patients to address questions of etiology, prognosis, and survivorship. Eligibility is limited to patients 18 years or older with a confirmed first stage 0-4 breast cancer diagnosis within the last year. Consent is completed via phone, patient portal, or in-person. Upon enrollment, a baseline questionnaire and blood collection are completed. Annual follow-up surveys that capture BC outcomes are sent to all living participants. The MCBDR cohort (N=9,215, enrolled between 2001 and 2023) is 99% female, with an average age at diagnosis of 58 years (SD=12.7). Currently, MCBDR has an average time since diagnosis of 9.8 years (SD=6.4). The participants are 94% white, and 55% live in Minnesota. At the time of baseline questionnaire completion, 77% were married, 84% had a bachelor’s degree or higher, and 8% reported financial hardship. Further, 35% reported a history of smoking, 11% consumed more than two drinks per day, and 9% reported fair or poor social relationships. Within MCBDR, 53% of the participants had stage 0 or 1 cancer at diagnosis, while 28% had stage 2, 9% stage 3, and 3% stage 4 BC. Tumors were triple negative in 9%, HER 2 positive in 9%, hormone receptor-positive and HER2 low or negative in 55%, and 27% had missing HER2 status. Pathological TNM staging was available on 98%, among which 33% were staged at T2 or higher and 27% were node-positive. Definitive BC surgery was completed at Mayo Clinic for 73%, with 35% undergoing mastectomies and 44% having lumpectomies. 74% were treated with radiation, 56% underwent chemotherapy, and 79% were treated with endocrine therapy. Clinical genetic testing results have been nurse-abstracted for 94% of the cohort. Of those known to be tested, 521 (6%) had a pathogenic or likely pathogenic mutation identified in a BC causing gene. In addition, whole exome sequencing was completed on 71% of MCBDR participants in 2020, in which 167 previously unknown pathogenic or likely pathogenic mutations were identified. After the initial diagnosis and active treatment phase, nurse abstraction identified 151 (2%) participants known to have been diagnosed with a contralateral BC diagnosis, and 4% known to have been diagnosed with a second primary other than breast. Recurrence in the same breast has been reported for 242 (3%), with 72% of those recurrences occurring within 5 years of initial diagnosis and another 19% occurring 5-10 years post diagnosis. Among the 1,262 (14%) who are deceased, 24% died from BC and 19% had distant metastases at diagnosis or a distant recurrence. Amongst all deceased, 6% died within 1 year of their diagnosis and 43% died within 5 years of diagnosis. For participants who died from BC, 10% died within 1 year of their diagnosis and 64% died within 5 years of diagnosis. MCBDR data has been used in numerous publications and is an essential resource for efficient observational research analyses. Citation Format: Nicole L. Larson, Janet Olson, Kathryn Ruddy, Fergus Couch, Denise Herman, Feven Abraha. Mayo Clinic breast cancer cohort: A valuable resource for breast cancer research [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7339.

Changes in Radiation Therapy: New Ultrahypofractionated Radiation, Repeat Breast Conservation Therapy in the Management of Breast Recurrence with Re-irradiation, Proton Therapy

Changes in Radiation Therapy: New Ultrahypofractionated Radiation, Repeat Breast Conservation Therapy in the Management of Breast Recurrence with Re-irradiation, Proton Therapy

A UK prospective multicentre decision impact, decision conflict and economic evaluation of the 21-gene assay in women with node+ve, hormone receptor+ve, HER2-ve breast cancer

BackgroundFor a tumour profiling test to be of value, it needs to demonstrate that it is changing clinical decisions, improving clinical confidence, and of economic benefit. This trial evaluated the use of the Oncotype DX Breast Recurrence Score® assay against these criteria in 680 women with hormone receptor-positive (HR+), HER2-negative early breast cancer with 1–3 lymph nodes positive (LN+) in the UK National Health Service (NHS).MethodsPrior to receipt of the Recurrence Score (RS) result, both the physician and the patient were asked to state their preference for or against chemotherapy and their level of confidence on a scale of 1–5. Following receipt of the RS result, the physician and patient were asked to make a final decision regarding chemotherapy and record their post-test level of confidence.ResultsReceipt of the RS result led to a 51.5% (95% CI, 47.2–55.8%) reduction in chemotherapy, significantly increased the relative and absolute confidence for both physicians and patients and led to an estimated saving to the NHS of £787 per patient.ConclusionThe use of the Oncotype DX assay fulfils the criteria of changing clinical decisions, improving confidence and saving money.