Early Breast Cancer Trialists ’ Collaborative Group Research Articles

Abstract PO5-02-11: Is There A Survival Benefit With Adjuvant Chemotherapy Use In Elderly Breast Cancer Patients? A Retrospective Study Using The National Cancer Database

Abstract Background Geriatric patients (Age >=65 years) with Breast Cancer (BC) face a unique challenge due to the relatively lower functional status, as well as co-existing comorbidities. Studies like the recently published meta-analysis by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) group provide irrefutable evidence for the recurrence free survival benefit of anthracycline and taxane based adjuvant chemotherapy (ACT) regimes in early-stage BC patients. However, the age range of the trials analyzed ranged between 46-55 years, with underrepresentation of the geriatric group. The question on whether ACT results in an overall survival (OS) benefit for the elderly remains at large, which we hope to answer through our study. Methods The 2019 National Cancer Database (NCDB) was used to extract patients aged >= 65 years with breast cancer. We included stage 1-3 patients and stratified them into those who received ACT (ACT+) and those who did not (ACT-). Patients who received ACT were identified from the columns that specified the times of events from diagnosis or from the column for systemic therapy-surgery sequence. Patients should have had definitive surgery for their BC management to be included. Odds Ratio (OR) from logistic regression was used to analyze the utility of ACT based on various factors. Kaplan Meier (KM) survival curves and Hazard Ratio (HR) estimates from multivariate cox model was used to compare OS outcomes. Results Our cohort had 866,071 (ACT+: 642721, ACT-:223350) patients. The age distribution showed that ACT+ had 86.45% in the 65-80 years group and 13.55% in the >80 years group. ACT- had 68.32% aged 65-80 and 31.68% >80 years. The distribution of various demographic, pathologic and clinical factors by ACT use are shown in Table 1. Factors associated with ACT use based on OR estimates are shown in Table 2. ACT use is more likely in younger age group (65-80), lower comorbidity score, poorly differentiated and undifferentiated tumors, ER/PR negativity, T2 and lymph node positivity, those who underwent partial mastectomy and regional lymph node surgery, and HER2 positivity. Both 5-year (86.3 vs 74.2%) and 10-year (66 vs 50.8) OS were better with ACT+ (Table 2). The HR using propensity score (PS) weighted cox model revealed a higher hazard rate on omitting ACT [1.436, 95% Confidence Interval (CI) 1.417,1.456, p< .0001] (Table 2). HR estimates between ACT- vs ACT+, stratified by subgroups [Age (65-80, >80), T stage, grade (G), HER2] favored ACT use in all groups except G1 tumors (Table 3). Discussion Our study using a large national database, supports the use of ACT in the geriatric BC population by showing a clear OS advantage of 15.2% at 10 years. This benefit was observed even in BC patients aged more than 80 years with a HR of 1.683 when compared to ACT-, as represented in Table 3. While the existing literature provides robust evidence for ACT use in situations such as a high oncotype recurrence score, our study provides real-world evidence from a population-based dataset to supports its use in the elderly, including those above 80 years. The geriatric assessment recommended by the American Society of Clinical Oncology guideline for geriatric oncology should be followed in this setting. Utilization of geriatric assessment tools among oncologists has been poor with a survey revealing that 60% of providers did not utilize these tools in making treatment decisions. Limitations of our study include the potential for missing confounding factors and the retrospective nature of the study using a large database. Table 1 Demographic, pathological, and clinical characteristics of the study population and their distribution based on ACT use. Table 2 Odds Ratio for ACT use, KM survival curves and HR estimates of ACT use Table 3 HR estimates of mortality for ACT- vs ACT+ stratified by various subgroups Citation Format: Prashanth Ashok Kumar, Metlapalli Venkata Sravanthi, Dongliang Wang, Danning Huang, Abirami Sivapiragasam. Is There A Survival Benefit With Adjuvant Chemotherapy Use In Elderly Breast Cancer Patients? A Retrospective Study Using The National Cancer Database [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 PO5-02-11.

Impact of oncoplasty in increasing breast conservation rates Post neo-adjuvant chemotherapy.

The essential goal of neoadjuvant chemotherapy (NACT) is to downstage the primary tumor making it amenable for breast conservation surgery (BCS). However, since the safety of this surgery is paramount, post-NACT breast conservation rates remain low. As per the recommendation of the 2018 Early Breast Cancer Trialists' Collaborative Group (EBCTCG) overview of long-term post-NACT follow-up, we have devised a protocol for imaging, localization, rad-path analysis, and documentation of radiotherapy techniques to ensure the safety of post-NACT breast conservation. This is a retrospective cohort of 180 breast cancer patients who received NACT and were operated on by a single surgical oncologist from 2015 to 2020. After selection based on published guidelines, patients were treated with neoadjuvant systemic (chemo or hormone) therapy. In cases where primary tumors responded and reduced to 1-2 cm in size mid-NACT, the residual tumors were localized by clips under ultrasound guidance and calcification was wire localized. All patients were treated using appropriate surgical and oncoplastic techniques where indicated. Negative margins were ensured by intra-operative rad-path analysis. Adjuvant chemotherapy and radiotherapy were given as per protocol. In 81 cases that required mastectomy at presentation, we were able to achieve a 72.8% post-NACT BCS rate with the help of oncoplasty. Overall, 142 of 180 (80%) patients were treated with breast conserving surgery of which 80% (121 of 142) were oncoplasty. Margins were assessed on intra-operative frozen and re-excised in the same setting. No positive margins were reported in final histopath of 142 breast conservation procedures. Post-operative complication rates after breast conservation in the first year were at 17% (24 of 142 including two major complications). Patient reported outcomes were satisfactory with increased satisfaction for breast conservation compared with immediate breast reconstruction. Employing oncoplastic breast surgery (OBS) techniques following stringent protocols for accurate localization of the residual tumor, intra-operative rad-path analysis, and adjuvant treatments, we show successful breast conservation in 72.8% of our mastectomy-qualified patients after downstaging by NACT. We also report satisfactory outcomes for post-NACT surgery, patient-reported satisfaction, and survival.

Whole Breast Irradiation in Comparison to Endocrine Therapy in Early Stage Breast Cancer-A Direct and Network Meta-Analysis of Published Randomized Trials.

Multiple randomized trials have established adjuvant endocrine therapy (ET) and whole breast irradiation (WBI) as the standard approach after breast-conserving surgery (BCS) in early-stage breast cancer. The omission of WBI has been studied in multiple trials and resulted in reduced local control with maintained survival rates and has therefore been adapted as a treatment option in selected patients in several guidelines. Omitting ET instead of WBI might also be a valuable option as both treatments have distinctly different side effect profiles. However, the clinical outcomes of BCS + ET vs. BCS + WBI have not been formally analyzed. We performed a systematic literature review searching for randomized trials comparing BCS + ET vs. BCS + WBI in low-risk breast cancer patients with publication dates after 2000. We excluded trials using any form of chemotherapy, regional nodal radiation and mastectomy. The meta-analysis was performed using a two-step process. First, we extracted all available published event rates and the effect sizes for overall and breast-cancer-specific survival (OS, BCSS), local (LR) and regional recurrence, disease-free survival, distant metastases-free interval, contralateral breast cancer, second cancer other than breast cancer and mastectomy-free interval as investigated endpoints and compared them in a network meta-analysis. Second, the published individual patient data from the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) publications were used to allow a comparison of OS and BCSS. We identified three studies, including a direct comparison of BCS + ET vs. BCS + WBI (n = 1059) and nine studies randomizing overall 7207 patients additionally to BCS only and BCS + WBI + ET resulting in a four-arm comparison. In the network analysis, LR was significantly lower in the BCS + WBI group in comparison with the BCS + ET group (HR = 0.62; CI-95%: 0.42-0.92; p = 0.019). We did not find any differences in OS (HR = 0.93; CI-95%: 0.53-1.62; p = 0.785) and BCSS (OR = 1.04; CI-95%: 0.45-2.41; p = 0.928). Further, we found a lower distant metastasis-free interval, a higher rate of contralateral breast cancer and a reduced mastectomy-free interval in the BCS + WBI-arm. Using the EBCTCG data, OS and BCSS were not significantly different between BCS + ET and BCS + WBI after 10 years (OS: OR = 0.85; CI-95%: 0.59-1.22; p = 0.369) (BCSS: OR = 0.72; CI-95%: 0.38-1.36; p = 0.305). Evidence from direct and indirect comparison suggests that BCS + WBI might be an equivalent de-escalation strategy to BCS + ET in low-risk breast cancer. Adverse events and quality of life measures have to be further compared between these approaches.

Abstract P2-02-01: Benefit of adjuvant bisphosphonates in early breast cancer treated with contemporary systemic therapy: A meta-analysis of randomized control trials

Abstract Introduction: Based on trials performed over a 25-year period, the Early Breast Cancer Trialists Collaborative Group (EBCTCG) identified a small but significant benefit of adjuvant bisphosphonates (BP) in reducing bone recurrence with a subsequent modest improvement in breast cancer-specific survival in post-menopausal women. Multiple studies show that contemporary event rates in early-stage breast cancer are much lower than those observed over a decade ago. This observation likely reflects the impact of modern adjuvant systemic therapy such as anthracycline and taxane chemotherapy and aromatase inhibitors. Therefore, re-evaluating the benefit of adjuvant bisphosphonate in the modern era is warranted. Methods: We reviewed reports of randomized trials of adjuvant BP that accrued patients exclusively beyond 2000 and extracted 5-year disease free survival (DFS) and overall survival (OS) in BP and control group arm along with hazard ratios (HR) when reported. The mean 5-year DFS and OS weighted by study sample size was calculated for each group. HR for DFS and OS were pooled in a meta-analysis using generic inverse variance and random effects modelling. Trial level absolute differences in DFS and OS between BP and control arms were calculated. Meta-regression comprising linear regression weighted by sample size (mixed effects) was then performed to explore association between disease and treatment related factors and absolute differences in benefit from BP. Quantitative significance was explored using methods described by Burnand et al. Analyses were performed using SPSS version 28 (IBM Corp, Armonk NY) and Review manager v5.4. Results: Twelve trials comprising 24109 patients were included in the analysis. Weighted mean DFS and OS in patients receiving BP were 85.8% and 91.7% respectively. For control group patients, these estimates respectively were 83.4% and 91.0%. For DFS, pooled HR across trials was 0.89 (0.81-0.97) with a 2.9% weighted mean difference favoring BP over control. Among patients receiving anthracycline and taxane based chemotherapy (n=3007), relative benefits were smaller; (HR DFS 0.94, 0.85-1.05). There was no significant OS benefit with BP (HR 0.92, 0.82-1.03) and this finding was observed irrespective of type of chemotherapy. The impact of BP on OS was smaller in both relative and absolute terms in studies with recruitment occurring more recently. Meta-regression results are shown in Table. There was lesser benefit in higher risk patients (node+, larger tumor size, ER-, grade 3 or those receiving chemotherapy). Overall, 1.13% patients experienced osteonecrosis related to BP therapy. Conclusions: Compared to EBCTCG data, relative and absolute benefit from BP is similar or modestly lower among more recent trials. Benefit from adjuvant BP appears smaller in patients treated with more contemporary adjuvant systemic therapy especially anthracycline and taxane containing chemotherapy. It is uncertain if the impact of BP on OS (rather than breast-cancer specific survival) is of a clinically meaningful magnitude. Despite de-escalated dosing compared to metastatic disease, osteonecrosis was observed in >1% of patients. It is possible that the benefits of BP are driven by patients with clinically low-risk disease rather than those with at high-risk. The balance between benefits and risks of adjuvant BP should be considered in individual patients. Table 1: Metaregression Results Citation Format: Abhenil Mittal, Faris Tamimi, Consolacion Molto Valiente, Massimo Di Iorio, Eitan Amir. Benefit of adjuvant bisphosphonates in early breast cancer treated with contemporary systemic therapy: A meta-analysis of randomized control trials [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-02-01.

Abstract P1-02-01: Comparing the efficacy of aromatase inhibitors vs tamoxifen in hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer: a systematic review and trial-level meta-analysis

Abstract Background: Five years of adjuvant endocrine therapy (ET) including aromatase inhibitors (AIs) and tamoxifen (TAM) is considered the standard of care in hormone receptor–positive, human epidermal growth factor–negative (HR+/HER2−) early breast cancer (eBC). Clinical practice guidelines recommend the use of an AI or TAM depending on menopausal status and clinical risk stratification. Although TAM is generally recommended and more commonly used in premenopausal women, there is mixed evidence for different clinical outcomes. Patient-level meta-analyses conducted by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) showed significantly lower rates of BC recurrence with AIs vs TAM. However, this was not specific to patients with HR+/HER2− eBC. This trial-level meta-analysis was conducted to compare AIs ± ovarian function suppression (OFS) vs TAM ± OFS in HR+/HER2−, pre- and postmenopausal patients with eBC. Methods: A systematic literature review (SLR) was conducted using key literature databases, ie, Embase, PubMed, and MEDLINE In-Process (from database inception to March 2022) and key conferences (2019-2021). Studies selected for the SLR were those that included either ≥80% of patients with HR+/HER2− eBC in the mixed patient population or subgroup data provided specifically for patients with HR+/HER2− eBC. Of these, randomized controlled trials (RCTs) investigating AI ± OFS vs TAM ± OFS and assessing disease-free survival (DFS) were included in the trial-level meta-analysis. This meta-analysis was conducted using the generic invariance method to obtain a pooled effect estimate (hazard ratio [HR]) together with its CI for DFS. This pooled estimate was calculated as a weighted average of the intervention effects estimated in the individual trials. Both fixed- and random-effect models (FEM, REM) were used to estimate the effect size. A base-case analysis was performed including all eligible trials. Three other scenario analyses were conducted: trials investigating only nonsteroidal AIs (NSAIs), assessing only premenopausal women, and assessing only postmenopausal women. Heterogeneity across the trials was assessed using I2 statistic. Results: A total of 5 RCTs comparing AI ± OFS vs TAM ± OFS were eligible for the meta-analysis (SOFT, HOBOE, BIG 1-98, N-SAS BC 03, Li 2019; additional information on rationale for exclusion of specific trials will be reported). Two studies assessing NSAI vs TAM included postmenopausal women, while 3 studies assessing AIs + OFS vs TAM ± OFS included premenopausal women. A total of 6623 patients were followed up for 34-97.2 months across these five trials. Heterogeneity was found to be low (I2 < 40%) across all scenarios. The base-case results (including all studies) using FEM significantly favored AIs ± OFS over TAM ± OFS, with a 29% reduction in risk of recurrence or death (pooled HR, 0.71 [95%CI, 0.64-0.80]). Similar results were observed with NSAIs ± OFS vs TAM ± OFS (HR, 0.73 [95% CI, 0.64-0.83]). Among premenopausal patients, the pooled HR for AIs + OFS vs TAM ± OFS was 0.66 (95% CI, 0.54-0.79). For postmenopausal women, the HR was 0.75 (95% CI, 0.65-0.87), favoring AIs over TAM. The findings for the base-case and different scenarios remained consistent when REM was used. Conclusions: This trial-level meta-analysis suggests significantly greater benefit with AIs than with TAM for HR+/HER2− eBC. Notably, AIs in combination with OFS are associated with a 34% reduction in risk of recurrence or death vs TAM ± OFS in premenopausal women; these results are aligned with the patient-level data findings of the EBCTCG. The findings indicate that AIs ± OFS are associated with a better DFS in the HR+/HER2− population, especially premenopausal women, than TAM ± OFS. Citation Format: Wolfgang Janni, Michael Untch, Nadia Harbeck, Joseph Gilgorov, William Jacot, Stephen K. Chia, Jean-Francois Boileau, Sina Haftchenary, Rhea Gupta, Namita Mishra, Purnima Pathak, Giuseppe Curigliano. Comparing the efficacy of aromatase inhibitors vs tamoxifen in hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer: a systematic review and trial-level meta-analysis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-02-01.

Bone-Targeted Agents and Metastasis Prevention

Simple SummaryBone metastases are common in cancer patients and the role of bone-targeted agents in prevention of metastasis have been evaluated in multiple clinical trials over the past 20 years. Results show that in breast cancer the use of adjuvant bisphosphonates (and possibly denosumab) reduce bone metastases and breast cancer deaths in postmenopausal women. These effects are in addition to the benefits associated with the use of standard adjuvant endocrine, cytotoxic and targeted treatments with prevention of one in six breast cancer deaths at 10 years. Similar benefits have not been observed in other cancers that typically spread to bone, such as prostate or lung cancers. Biomarkers that can predict patient benefit from the use of bone targeted treatments in the adjuvant setting are being evaluated. Currently, tumour expression of the transcription factor, MAF, seems to be the most promising biomarker; benefits from adjuvant bisphosphonates are seen in the 80% of patients with normal levels of expression irrespective of menopausal status, while over-expression is associated with a poor prognosis and a higher rate of visceral metastases.The use of bone-targeted treatments has transformed the clinical care of many patients with metastatic breast cancer. In addition, due to the profound effects of bisphosphonates and denosumab on bone physiology and the bone microenvironment, the potential of bone-targeted agents to modify the process of metastasis has been studied extensively. Many adjuvant trials with bisphosphonates in early breast cancer have been performed. Variable outcomes in terms of disease recurrence have been reported, with any treatment benefits apparently influenced by the age and menopausal status of the patients. The Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) conducted a meta-analysis of individual patient data from all available randomised trials to investigate this observation further. This meta-analysis failed to show any benefits of adjuvant bisphosphonates in premenopausal women, but highly significant improvements in bone recurrence (RR = 0.72; 95% CI 0.60–0.86, 2p = 0.0002) and breast cancer mortality (RR = 0.82; 95% CI 0.73–0.93, 2p = 0.002) were seen in the 11,767 postmenopausal women included in the meta-analysis. As a result, clinical guidelines recommend the incorporation of adjuvant bisphosphonates that inhibit osteoclast activity into routine clinical care. Denosumab, which has similar effects on bone cell physiology, appears not to consistently influence disease outcomes, perhaps suggesting that it is the “off target” effects of bisphosphonates on immune function and the biological processes involved in metastasis that are important. Predictive biomarkers beyond menopause are being sought and assessment of the transcription factor MAF (mesenchymal aponeurotic fibrosarcoma gene) appears to identify patients able to benefit from the addition of a bisphosphonate to standard adjuvant anticancer therapies.

Locoregional Management of Breast Cancer: A Chronological Review.

Locoregional management of breast cancer is founded on evidence generated over a vast time period, much longer than the career span of many practicing physicians. Oncologists rely on specific patient and tumour characteristics to recommend modern-day treatments. However, some of this information may not have been available during prior periods in which the evidence was generated. For example, the comprehensive Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) meta-analyses published in the 2000s typically included older trials accruing patients between the 1960s and 1980s. This raises some uncertainty about whether conclusions from studies conducted in prior eras are as relevant or applicable to modern-day patients and treatments. Reviewing the chronological order and details of the evidence can be beneficial to understanding these nuances. This review discusses the evolution of locoregional management through some key clinical trials. We aim to highlight the time period in which the evidence was generated and emphasize the 10-year outcomes for the comparability of results. Evidence supporting surgical management of the breast and axilla, as well as details of radiotherapy are discussed briefly for all stages of breast cancer.

Abstract PS6-08: The PORTRET-tool: A prediction tool for older patients with breast cancer that predicts recurrence, survival and other-cause mortality

Abstract Introduction Previous studies have shown that available tools such as ‘Adjuvant Online!” are not able to accurately predict the prognosis of patients aged 65 years or older with breast cancer. Furthermore, all available tools predict prognosis in terms of recurrence-free survival or overall survival, whilst the risk of other-cause mortality is often high in the older patient with breast cancer. This is highly relevant as it may influence treatment decisions. Patient characteristics such as comorbidity and various geriatric variables have shown to be predictive for these outcomes and could enhance the precision of prognostic tools for this target population. The objective of this study was to develop a prediction tool for recurrence, survival and other-cause mortality for older patients with breast cancer who received locoregional treatment, with incorporation of patient-, tumor- and geriatric variables. The tool additionally predicts expected benefits of systemic treatment. Methods Data from the large population-based FOCUS cohort was used, consisting of consecutive breast cancer patients in the South-Western part of the Netherlands, diagnosed between 1997 and 2004, aged 65 years and older. It contains detailed information on tumor characteristics, treatment, comorbidity and geriatric parameters. We developed a risk prediction model using a Cox proportional hazards regression model for overall survival and cause-specific Cox proportional hazards models for recurrence and other-cause mortality (defined as mortality without recurrence). The included predictors were derived from the PREDICT tool (consisting of age and various tumor variables), since this tool was previously shown to have the best performance in older adults so far. Predictors were complemented with comorbidity and geriatric variables. Discrimination accuracy was evaluated using time-dependent area under the curve (AUC). The potential annual benefit of chemotherapy was calculated assuming a relative risk of chemotherapy on recurrence of 0.7, derived from data from the most recent updates of the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). Additional benefit of endocrine treatment will be included in further development of the tool. Results A total of 2,744 patients were included for the initial development. For all patients, 5-year follow-up was complete with a high event-rate including 343 recurrences and 831 total deaths of which 586 without recurrence. The strongest predictors for overall survival and non-recurrence mortality were age (HR = 2.14, 95% CI: 1.89 - 2.43 and HR = 2.87, 95% CI: 2.46 - 3.35, respectively) and dementia (HR = 1.52, 95% CI: 1.16 - 1.99 and HR = 1.9, 95% CI: 1.49 - 2.65, respectively), and for recurrence, nodal status (HR = 1.80, 95% CI: 1.45 - 2.24) and tumor grade (HR = 2.96, 95% CI: 1.88 - 4.66). The time-dependent AUC at 5 years for recurrence-specific and other-cause mortality were 0.78 (95% CI: 0.76 - 0.81), and 0.75 (95% CI: 0.72 - 0.78), respectively. The AUC for overall survival was 0.75 (95% CI: 0.72 - 0.78). External validation is currently being performed in a large dataset retrieved from the national cancer registry (N= 13,631). These results will be presented during the symposium. Conclusion We have developed a model for predicting 5-year recurrence, other-cause mortality and overall survival, including expected benefits of adjuvant treatment, for older patients with breast cancer, with a good discrimination performance within a large-population based cohort. To our knowledge, this is the first model specifically designed for the older population, including competing risk as a predicted outcome and with incorporation of geriatric variables. Citation Format: Willeke van der Plas-Krijgsman, Daniele Giardiello, Hein Putter, Ewout W Steyerberg, Esther Bastiaannet, Anne M Stiggelbout, Simon P Mooijaart, Johanneke EA Portielje, Gerrit J Liefers, Nienke A de Glas. The PORTRET-tool: A prediction tool for older patients with breast cancer that predicts recurrence, survival and other-cause mortality [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-08.

Estrogens Determine Adherens Junction Organization and E-Cadherin Clustering in Breast Cancer Cells via Amphiregulin.

SummaryEstrogens play an important role in the development and progression of human cancers, particularly in breast cancer. Breast cancer progression depends on the malignant destabilization of adherens junctions (AJs) and disruption of tissue integrity. We found that estrogen receptor alpha (ERα) inhibition led to a striking spatial reorganization of AJs and microclustering of E-Cadherin (E-Cad) in the cell membrane of breast cancer cells. This resulted in increased stability of AJs and cell stiffness and a reduction of cell motility. These effects were actomyosin-dependent and reversible by estrogens. Detailed investigations showed that the ERα target gene and epidermal growth factor receptor (EGFR) ligand Amphiregulin (AREG) essentially regulates AJ reorganization and E-Cad microclustering. Our results not only describe a biological mechanism for the organization of AJs and the modulation of mechanical properties of cells but also provide a new perspective on how estrogens and anti-estrogens might influence the formation of breast tumors.

377A Poster - Factors affecting locoregional recurrence rate of breast conserving surgery in patients with neoadjuvant chemotherapy

Background: Breast conserving surgery(BCS) is preferred over traditional mastectomy for better cosmetic and non-inferior oncological outcome. BCS is best indicated for early stage breast cancer with relatively small tumor size. Neo-adjuvant chemotherapy(NAC) helps downstaging locally advanced breast cancer and increase the possibility for BCS. However, recent meta-analysis from the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) showed a higher locoregional recurrence(LLR) rate in the NAC group than in the adjuvant chemotherapy group. Thus, the aim of this study was to retrospectively explore the factors affecting the LRR rate in breast cancer patients receiving BCS after NAC.

13 Oral - Safety of pre-pectoral breast reconstruction followed by post mastectomy radiotherapy

Background: Implant-based breast reconstruction (IBBR) after mastectomy either with TE or DTI in pre-pectoral position has been widely accepted. The pre-pec breast reconstruction, in fact, spares muscles, preserving the natural anatomy and reduces post-operative pain. Moreover, the pre-pec approach is associated to a decreased risk of capsular contracture and animation deformities. An increasing number of women, who undergo IBBR, will require post mastectomy radiotherapy (PMRT), since the meta-analysis of Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) confirmed a significant reduction of both local recurrence and breast cancer mortality in patients with pathological nodal involvement and locally advanced cancer.

Validation of MAF biomarker for response prediction to adjuvant bisphosphonates in 2 clinical trials: AZURE and NSABP-B34.

513 Background: An Early Breast Cancer Trialists' Collaborative Group (EBCTCG) meta-analysis indicates that adjuvant bisphosphonates increase time to bone recurrence and survival in postmenopausal breast cancer patients, but results of individual trials have been inconclusive. Retrospective analyses of AZURE, a trial of adjuvant zoledronic acid, showed MAF (a transcription factor of the AP-1 family) amplification status predicted bisphosphonate benefit independently of menopause for invasive disease-free survival (IDFS) and overall survival (OS). Validation of MAF amplification status as a potential companion diagnostic for adjuvant bisphosphonates was confirmed using NSABP-B34 specimens. Methods: The randomized, placebo-controlled NSABP B-34 study of women with stage 1-3 breast cancer were assigned to adjuvant systemic therapy plus oral clodronate 1600 mg daily or placebo for 3 years. The primary endpoint was disease-free survival (DFS) with overall survival (OS) as a secondary outcome. MAF amplification was assessed by fluorescence in-situ hybridization on anonymized sections of breast tumor tissue in all patients with tumor samples and performed in a laboratory blind to treatment assignment. Protocol and analysis plans were pre-specified. Disease outcomes were analysed using intention to treat principles. Results: 2496 B-34 patients contributed tumor samples (from 2001-2004), of whom 1883 (75%) were evaluable (947 placebo and 936 clodronate). 1515 (80%) tumors were MAF negative (766 placebo and 749 clodronate) and 368 were MAF positive. At median follow-up of 108 months, MAF was prognostic for DFS, OS and bone-metastasis-free survival in the control group (MAF-positive vs MAF-negative: HRDFS=1·39, 95%CI 1·01-1·92; p=0.045; HROS=1·59, 95%CI 1·08-2·33; p=0.018; HRBM=2·03, 95%CI 1·13-3·68; p=0.016). In patients with MAF-negative tumors, clodronate gave higher DFS and OS than controls at 60 months (HRDFS=0·70, 95%CI 0·51-0·94; p=0.020 and HROS=0·59, 95%CI 0·37-0·93; p=0.024), the latter maintained through follow-up (HROS=0·74, 95%CI 0·54-1.00; p=0.047), but not in patients with MAF-positive tumors - consistent with previous AZURE results. Conclusions: MAF benefit prediction from adjuvant bisphosphonates was confirmed using specimens from 2 randomized clinical trials (AZURE and NSABP-B-34) conducted and analyzed in similar manner using the same validated tests and clinical endpoints. These results are evidence towards introducing MAF testing into clinical practice.

Influence of Competing Risks on Estimates of Recurrence Risk and Breast Cancer-specific Mortality in Analyses of the Early Breast Cancer Trialists Collaborative Group

Early-stage breast cancer (BC) is a curable disease with many patients dying of causes other than BC. The influence of non-BC death and other competing risks on the interpretation of Kaplan-Meier (KM)-based analyses for BC-specific outcomes are unknown. We searched the Oxford University website to identify all meta-analyses published by the Early Breast Cancer Trialists Collaborative Group (EBCTCG) between 2005 and 2018. The potential influence of competing risks was estimated using a validated multivariable linear model that predicts the difference between KM and cumulative incidence function (CIF) on estimates of BC-specific outcomes. The initial search identified 14 EBCTCG papers, 10 (71%) reported data on BC and competing events. Eight (80%) had a relative difference between KM and the competing risk adjusted estimates exceeding 10%. The median relative difference was 28.4% for local-recurrence; 16.8% for distant-recurrence, and 6.7% for BC-specific mortality. There was a 18.9% relative difference between KM and CIF adjusted analyses beyond 10 years. The use of KM-based methods when competing risks are present biases risk estimates in studies of early BC especially for uncommon outcomes such as local recurrence. The use of CIF to calculate BC-specific outcomes may be preferable in this setting.

Abstract GS2-04: Improvements in long-term outcome for women with estrogen receptor positive (ER+) early stage breast cancer treated with 5 years of endocrine therapy: Analyses of 82,598 women in the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) database

Abstract Background: For women with ER+ early stage breast cancer who are disease-free after 5 years of scheduled endocrine therapy, recurrences occur at a steady rate to at least year 20 from diagnosis, and are strongly correlated with tumor and nodal status (TN). For women diagnosed in 1976-2011, 20-year distant recurrence (DR) risk was 13%, 20%, and 34% for T1N0, T1N1-3, and T1N4-9 disease, respectively (Pan et al NEJM 2017). Using updated data, we investigated whether DR risk is lower for women diagnosed more recently. Methods: Kaplan-Meier and Cox regression analyses, stratified by trial, TN status and treatment, included 82,598 women with ER+ breast cancer from 108 trials who were alive and disease free after 5 years of scheduled endocrine therapy, 19,675 more than in the previously published dataset, of whom 11,391 were diagnosed since 2005. Results: Estimates of DR during the period from 5 to 20 years were 1% to 2% lower in the updated dataset than reported in 2017. Compared to earlier years (before 1995), the hazard ratio (HR) for DR in years 5-9 was 0.83 (95%CI 0.77 - 0.90) in women diagnosed in 1995-99, decreasing to 0.64 (0.59 - 0.70) in 2000-04, and to 0.58 (0.52 - 0.65) in 2005-12. Those diagnosed after 2000 (median follow-up after year 5 = 2.7, IQR 1.1-4.3 years) had a 30% lower risk of DR (HR = 0.70 (95% CI 0.66 - 0.75) compared with women diagnosed before 2000 (median follow-up after year 5 = 6.1, IQR 4.4-9.9 years). The recurrence risk in years 5-10 after diagnosis in women diagnosed after 2000 was 3% for T1N0 and 5% for T2N0, with few events recorded after year 10. If these recurrence rates continue at the same rate, 20-year risk of DR for women diagnosed after 2000 is projected to be 8% and 14% for T1N0 and T2N0 stages, respectively, compared with 13% and 19% for those diagnosed before 2000. More detailed analyses and investigation of factors influencing the improvements in outcome will be presented. Conclusion: The risk of DR at 20 years after diagnosis for women with node-negative ER+ early stage breast cancer, who discontinue endocrine therapy at 5 years is likely to be about a third lower now than in our previous report. However, long-term follow-up of patients diagnosed more recently is required to accurately characterize long-term recurrence risks. Reference: Pan H, Gray R, Braybrooke J, Davies C, Taylor C, McGale P, et al. 20-year risks of breast-Cancer recurrence after stopping endocrine therapy at 5 years. N Engl J Med. 2017;377:1836-46. Citation Format: Hongchao Pan, Jeremy Braybrooke, Richard Gray, Richard Peto, Rosie Bradley, Robert Hills, Jonas Bergh, Sandra M Swain, Mitchell Dowsett, Daniel F Hayes, Richard D Gelber, for the EBCTCG. Improvements in long-term outcome for women with estrogen receptor positive (ER+) early stage breast cancer treated with 5 years of endocrine therapy: Analyses of 82,598 women in the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) database [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS2-04.

Clinical benefits of bone targeted agents in early breast cancer

Through their profound effects on the bone microenvironment, bone targeted treatments can potentially modify the process of metastasis and have important effects on disease outcomes as well as on bone health. The Early Breast Cancer Trialists Collaborative Group (EBCTCG) evaluated the effect of adjuvant bisphosphonates in early breast cancer by performing a meta-analysis of individual patient data (n = 18,766) from all available randomized trials initiated between the early 1990s until 2006. In postmenopausal women, bisphosphonates reduced bone recurrence (RR = 0.72; 95%CI 0.60-0.86, 2p = 0.0002) and breast cancer mortality (0.82; 95%CI 0.73-0.93, 2p = 0.002); no effects on disease outcomes could be identified in premenopausal women. Somewhat surprisingly, these effects could not be reproduced in the large adjuvant trial of denosumab (DCARE). In this study, neither bone metastasis free survival (the primary endpoint) or disease-free survival were improved by the addition of this targeted antibody inhibitor of osteoclast activity. Efforts are ongoing to try to understand the biologic implications of these results. For now, the use of denosumab in early cancers is limited to its use for fracture prevention using the 60mg every 6 months dosing schedule.

Influence of competing risks on estimates of recurrence risk and breast cancer-specific mortality in analyses of the Early Breast Cancer Trialists Collaborative Group.

533 Background: Early stage breast cancer is a curable disease with the majority of patients dying of causes other than breast cancer. The influence of these competing risks of death on the interpretation of Kaplan-Meier(KM)-based analyses such as those performed by the Early Breast Cancer Trialists Collaborative Group (EBCTCG) are unknown. Methods: We searched the Clinical Trial Service Unit and Epidemiological Studies Unit website at Oxford University to identify all meta-analyses published by the EBCTCG between 2005 and 2018. Studies were included if they contained KM curves with risk estimates for either breast cancer mortality and/or breast cancer recurrence. The potential influence of competing risks was estimated using a validated multivariate linear model that predicts the amount that the KM risk estimates are biased relative to outcome risk measured with the cumulative incidence function (CIF). Results: The initial search identified 14 analyses published by the EBCTCG with 10 of the 14 studies (71%) susceptible to competing risk bias cited both the number of events of interest and competing events. Eight of the ten studies (80%) had a relative difference between the KM estimate and the competing risk adjusted estimate of more than 10% while 2 of 10 (20%) had a difference of less than 10%. The relative difference between the KM and adjusted estimates was 28.4% for local recurrence, 16.8% for distant recurrence, and 6.7% for breast cancer-specific mortality. There was 2.2% difference between KM and adjusted analyses between 0-4 years and 18.9% beyond 10 years of follow up. Use of KM and CIF-based analysis did not influence treatment effect in the majority of included studies. Conclusions: This study provides estimates for the overestimation of risk in Kaplan-Meier analyses resulting from failure to address competing risk bias. CIFs are more appropriate to measure outcome risk over time and should be used especially for long-term follow-up studies and for analysis of rare events.

Influence of Competing Risks on Estimates of Recurrence Risk and Breast Cancer-Specific Mortality in Analyses of the Early Breast Cancer Trialists Collaborative Group

Introduction: Early stage breast cancer is a curable disease with many patients dying of causes other than breast cancer. The influence of these competing risks of death on the interpretation of Kaplan-Meier (KM)-based analyses for other outcomes by the Early Breast Cancer Trialists Collaborative Group (EBCTCG) are unknown. Methods: We searched the Clinical Trial Service Unit and Epidemiological Studies Unit website at Oxford University to identify all meta-analyses published by the EBCTCG between 2005 and 2018. Studies were included if they risk estimates for either breast cancer mortality and/or breast cancer recurrence based on KM analyses and reported competing events. The potential influence of competing risks was estimated using a validated multivariate linear model that predicts the difference between KM and cumulative incidence function (CIF) on estimates of breast cancer-specific outcomes. Results: The initial search identified 14 analyses published by the EBCTCG, 10 of which (71%) reported data on breast cancer and competing events. Eight of the ten studies (80%) had a relative difference between the KM and the competing risk adjusted estimates exceeding 10%. The median (range) relative difference between the KM and adjusted estimates was: 28.4% for local recurrence; 16.8% for distant recurrence, and 6.7% for breast cancer-specific mortality. There was a 2.2% relative difference between KM and CIF adjusted analyses between 0-4 years of follow-up and 18.9% beyond 10 years. Use of KM vs. CIF-based analysis did not influence treatment effect in most included studies. Conclusions: The use of KM-based methods when competing risks are present biases risk estimates in studies of early breast cancer. Future studies should exclusively use the CIF to calculate breast cancer specific outcomes. Funding: N/A Declaration of Interest: Dr. Eitan AMIR reports personal fees from Genentech/Roche, personal fees from Apobiologix, personal fees from Myriad Genetics, personal fees from Agendia, outside the submitted work. Ethical Approval: This study was exempt from institutional review board approval since it used publicly available data exclusively.

Optimise not compromise: The importance of a multidisciplinary breast cancer patient pathway in the era of oncoplastic and reconstructive surgery.

Modern breast cancer care is a complex multidisciplinary undertaking in which the integrated function of multiple constituent parts is critical, and where changes to one therapeutic component may profoundly influence the delivery and outcomes of another. Oncoplastic and reconstructive breast surgery has evolved in the era of longer survival rates for women with breast cancer and aims to enhance oncological and cosmetic outcomes. However, concurrently there has been an expansion in the indications for post-mastectomy radiation therapy (Abdulkarim et al., 2011; Early Breast Cancer Trialists' Collaborative Group (EBCTCG), 2014; Poortmans et al., 2015; Wang et al., 2011), the recognition of several biologically distinct breast cancer subtypes (Perou et al., 2000; Sørlie et al., 2001, 2003; Cheang et al., 2008, 2009; Sotiriou et al., 2003; Millar et al., 2011; Blows et al., 2010; Schnitt, 2010; Haque et al., 2012; Dai et al., 2015) and the development of recommendations for prophylactic surgery for high-risk women, including BRCA-mutation carriers (James et al., 2006; Domchek et al., 2010). Primary systemic therapy is increasingly utilised yet has varying efficacy depending on tumour biology (Cortazar et al., 2014). In this paper we review the evidence which informs the multidisciplinary team opinion in the era of oncoplastic and reconstructive breast surgery. We aim to describe an optimal multidisciplinary approach which balances competing risks of multimodal therapies to optimise oncological and cosmetic outcomes.

Estimating the risk of lung cancer and cardiac mortality from doses to the lung and heart from modern tangent-only breast radiotherapy

AbstractPurposeThe Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) reported that the risks of breast cancer treatment in woman smokers may outweigh the benefits. The data used doses from published reports using a variety of treatment techniques. In our study, the risks of lung cancer and heart disease were determined from a modern era tangential-only technique.Methods and materialsDoses to the lung and heart were obtained for tangential radiotherapy to the breast or chest wall. The risk of lung cancer incidence and cardiac mortality were calculated by taking the ratio of our doses to those published by the EBCTG.ResultsA total of 77 women were identified meeting our inclusion criteria. The mean combined whole lung dose was 2·0 Gy. The mean whole heart dose was 0·9 Gy. The estimated risk of lung cancer and cardiac mortality in a 50-year-old life-long smoker was estimated to be 1·5 and <1%, respectively.ConclusionsTangential only radiotherapy delivered substantially lower doses to the combined whole lung and whole heart than those reported by the EBCTCG. In this cohort, the risks of radiation induced lung cancer and heart disease are outweighed by the benefits of radiotherapy even in those that are smokers.

Anthracycline Use for Early Stage Breast Cancer in the Modern Era: a Review.

Anthracycline-based regimens have been an important treatment component for patients with breast cancer. As demonstrated in the last Early Breast Cancer Trialists' Collaborative Group (EBCTCG) meta-analysis, anthracycline-based regimens decrease breast cancer mortality by 20-30%. Anthracycline toxicities include the rare-but potential morbid-cardiotoxicity or leukemogenic effect, and the almost universal-but very distressing-alopecia. Due to potential toxicities, and large number of patients being exposed, several worldwide trials have re-examined the role of anthracycline-based regimens in the management of breast cancer. Current literature supports that anthracyclines are not required for all patients with breast cancer and should be avoided in those with high cardiac risk. Recent results from the ABC trials suggest that anthracyclines should not be spared for patients with triple negative breast cancer (regardless of axillary node involvement) or HER2-/ER+ with significant node involvement. Based on current literature, for HER2-negative patients with low-risk breast cancer, anthracyclines could be spared with regimens such as cyclophosphamide, methotrexate, and fluorouracil (CMF) or docetaxel and cyclophosphamide (TC). Patients with intermediate or high-risk breast cancer should be considered for anthracycline-based regimens based on other factors such as age, comorbidities, tumor grade, lymphovascular invasion, and genomic profiling. Patients with HER2-positive breast cancer with low risk could be treated with paclitaxel and trastuzumab. For the remaining patients with HER2 overexpression, while docetaxel, carboplatin, and trastuzumab (TCH) has demonstrated to improve disease-free survival (DFS), anthracycline-containing regimens should be discussed, especially for those with very high-risk breast cancer. Although several biomarkers, such as topoisomerase II (TOP2A) and chromosome 17 centromeric duplication (Ch17CEP) have been proposed to predict benefit from anthracycline regimens, further research is required to delineate their proper utility in the clinical setting.