ER-negative Disease Research Articles

Pregnancy-Related Factors and Breast Cancer Risk for Women Across a Range of Familial Risk

Few studies have investigated whether the associations between pregnancy-related factors and breast cancer (BC) risk differ by underlying BC susceptibility. Evidence regarding variation in BC risk is critical to understanding BC causes and for developing effective risk-based screening guidelines. To examine the association between pregnancy-related factors and BC risk, including modification by a of BC where scores are based on age and BC family history. This cohort study included participants from the prospective Family Study Cohort (ProF-SC), which includes the 6 sites of the Breast Cancer Family Registry (US, Canada, and Australia) and the Kathleen Cuningham Foundation Consortium (Australia). Analyses were performed in a cohort of women enrolled from 1992 to 2011 without any personal history of BC who were followed up through 2017 with a median (range) follow-up of 10 (1-23) years. Data were analyzed from March 1992 to March 2017. Parity, number of full-term pregnancies (FTP), age at first FTP, years since last FTP, and breastfeeding. BC diagnoses were obtained through self-report or report by a first-degree relative and confirmed through pathology and data linkages. Cox proportional hazards regression models estimated hazard ratios (HR) and 95% CIs for each exposure, examining modification by PARS of BC. Differences were assessed by estrogen receptor (ER) subtype. The study included 17 274 women (mean [SD] age, 46.7 [15.1] years; 791 African American or Black participants [4.6%], 1399 Hispanic or Latinx participants [8.2%], and 13 790 White participants [80.7%]) with 943 prospectively ascertained BC cases. Compared with nulliparous women, BC risk was higher after a recent pregnancy for those women with higher PARS (last FTP 0-5 years HR for interaction, 1.53; 95% CI, 1.13-2.07; P for interaction < .001). Associations between other exposures were limited to ER-negative disease. ER-negative BC was positively associated with increasing PARS and increasing years since last FTP (P for interaction < .001) with higher risk for recent pregnancy vs nulliparous women (last FTP 0-5 years HR for interaction, 1.54; 95% CI, 1.03-2.31). ER-negative BC was positively associated with increasing PARS and being aged 20 years or older vs less than 20 years at first FTP (P for interaction = .002) and inversely associated with multiparity vs nulliparity (P for interaction = .01). In this cohort study of women with no prior BC diagnoses, associations between pregnancy-related factors and BC risk were modified by PARS, with greater associations observed for ER-negative BC.

Real-world duration of interruptions in imaging and endocrine therapy (ET) after pregnancy in early-stage estrogen receptor (ER) positive breast cancer (BC).

11157 Background: Pre-menopausal women with early-stage ER-positive BC often desire the option for future fertility. The POSITIVE trial demonstrated that a pause in ET to conceive is safe. However, the real-world durations of these pauses, as well as how many patients resume ET, are unclear. Additionally, there are limited data about when and if women reestablish imaging surveillance after childbirth. Methods: We generated a cohort of BC patients with a pregnancy-related ICD diagnosis from the Oncoshare registry. This registry merges EMR and California Cancer Registry data for patients treated in the Stanford Health Care Alliance which includes an academic hospital, a community hospital, and a community practice network. Included patients had ≥1 pregnancy after a diagnosis of stage 0-3 ER-positive BC. Chart review confirmed pregnancy and was used to abstract treatment information. Data are presented as unadjusted percentages or medians with interquartile ranges (IQR). Among patients without bilateral mastectomies, we compared time from delivery to first imaging (MRI or mammogram) for those who breastfed vs not and those who restarted ET vs not using the Wilcoxon rank sum test. Results: Of the 317 charts reviewed, 71 were included. Most exclusions were due to no pregnancy (46%) or ER-negative disease (25%). Year of diagnosis ranged from 1994 to 2020, with the majority (79%) from 2010 to 2020. Median age at diagnosis was 33 years (IQR 30-35). The distribution of stages was 18% in situ disease, 51% stage 1, 17% stage 2, 14% stage 3. 23% (16/71) of women never started ET, with 14 attributing this decision to desiring pregnancy. Among the 55 women who started ET, 75% received tamoxifen without ovarian suppression (OS). After 2015, use of OS became more prevalent (45% of ET), coinciding with the emergence of the SOFT/TEXT data. The median time from ET onset to a pause for pregnancy was 32 months (IQR 22-53), and the median ET pause to delivery was 23 months (IQR 14-48). We recorded 90 pregnancies resulting in 85 live births. After delivery of their first child, the median follow-up was 3.8 years (IQR 2.0-6.8). 40% of patients never restarted ET. Those who did restart did so at a median of 5 months (IQR 3-11) post-delivery. Imaging surveillance resumed for 42% (27/64) at a median of 6 months post-delivery [IQR 3-11]. Time from delivery to imaging was similar between those who restarted ET and those who did not (p=0.91), and between those who breastfeed and those who did not (p=0.42). Conclusions: These data support prior work showing that fertility concerns strongly influence adjuvant therapy choice in ER-positive BC. The ET resumption rate after pregnancy was lower in our analysis compared to the POSITIVE trial (73% vs. 40%). Only 42% of women resumed surveillance imaging. This points to clear gaps between the clinical trial population and the real-world clinical setting.

Use of surgery for de novo metastatic breast cancer (mBC).

1590 Background: In the U.S., locoregional surgery for de novo mBC was common in the 1990s and 2000s, but subsequent prospective data did not show a survival advantage. Current guidelines recommend surgery only for symptom control. We investigated trends in the use of surgery (lumpectomy or mastectomy) for mBC from 2010 to 2019 using SEER and institutional data, aiming to identify factors that correlate with variability in surgery use. Methods: We included all de novo mBC diagnoses from SEER-17 from 2010-2019. The primary outcome was receipt of surgery, and we included year of diagnosis, demographic (race/ethnicity, age, marital status, median household income in the patient’s county, and urban/rural residence), and disease factors (estrogen receptor (ER) and HER2 status, tumor size, and presence of visceral metastases) in the multivariable logistic regression. We similarly identified all de novo mBC diagnoses from Oncoshare, which merges EMR and California Cancer Registry (CCR) data for patients treated in the Stanford Health Care Alliance. For Oncoshare inclusion a patient must have an encounter with Stanford and be in CCR; however, a patient does not have to receive all cancer care at Stanford. In this analysis, we included distance to the cancer center and insurance status. Results are presented as unadjusted percentages or odds ratios with 95% confidence intervals. Results: In SEER (n = 24,146), the use of surgery for mBC declined from 41% in 2010 to 22% in 2019, a trend also observed in the institutional data (n = 785). Surgery rates were highest in younger patients and declined with each decade of life (44% for those in their 30s vs 19% for those &gt; 80). Surgery was more common in tumors &gt; 2 cm, ER-negative disease, and in patients without visceral metastases. In SEER, patients from counties with median incomes &lt; $50,000 were more likely to have surgery than those from counties with incomes &gt; $75,000 (36% vs 27%; OR: 1.3 [1.2-1.5]). Rural patients were more likely to have surgery than urban patients (34% vs 30%; OR: 1.1 [1.0-1.3]). Unmarried persons had lower odds of surgery than married persons (OR: 0.8 [0.7-0.9]). The institutional data reproduced the findings of the SEER analysis, except that a relationship between surgery and marital status and income was not observed. In the institutional data, patients living farther from the Stanford Cancer Center ( &gt; 100 km) were more likely to have surgery (40% vs 32%; OR 2.1 [1.2-3.8]). Conclusions: The use of surgery for de novomBC decreased dramatically in the 2010s from 41% to 22%. All demographics saw a reduction; however, younger, and married patients underwent surgery at higher rates. Patients from lower-income and rural counties—areas typically with less access to care—were also more likely to have surgery. The institutional analysis showed that a greater distance from an urban hospital network correlated with increased odds of surgery. These patterns suggest differential care provision in rural areas for patients with mBC.

Elucidating the Role of MicroRNA-18a in Propelling a Hybrid Epithelial-Mesenchymal Phenotype and Driving Malignant Progression in ER-Negative Breast Cancer.

Epigenetic alterations that lead to differential expression of microRNAs (miRNAs/miR) are known to regulate tumour cell states, epithelial-mesenchymal transition (EMT) and the progression to metastasis in breast cancer. This study explores the key contribution of miRNA-18a in mediating a hybrid E/M cell state that is pivotal to the malignant transformation and tumour progression in the aggressive ER-negative subtype of breast cancer. The expression status and associated effects of miR-18a were evaluated in patient-derived breast tumour samples in combination with gene expression data from public datasets, and further validated in in vitro and in vivo breast cancer model systems. The clinical relevance of the study findings was corroborated against human breast tumour specimens (n = 446 patients). The down-regulated expression of miR-18a observed in ER-negative tumours was found to drive the enrichment of hybrid epithelial/mesenchymal (E/M) cells with luminal attributes, enhanced traits of migration, stemness, drug-resistance and immunosuppression. Further analysis of the miR-18a targets highlighted possible hypoxia-inducible factor 1-alpha (HIF-1α)-mediated signalling in these tumours. This is a foremost report that validates the dual role of miR-18a in breast cancer that is subtype-specific based on hormone receptor expression. The study also features a novel association of low miR-18a levels and subsequent enrichment of hybrid E/M cells, increased migration and stemness in a subgroup of ER-negative tumours that may be attributed to HIF-1α mediated signalling. The results highlight the possibility of stratifying the ER-negative disease into clinically relevant groups by analysing miRNA signatures.

Abstract PS06-09: Fragmentomic analysis of a circulating tumor DNA targeted cancer gene panel discriminates ER status in metastatic breast cancer liquid biopsies

Abstract Background: Circulating tumor DNA (ctDNA) isolated from the peripheral blood of patients with cancer is now routinely used in the clinic to detect tumor somatic mutations, with multiple ctDNA-targeted sequencing panels commercially available for Food and Drug Administration (FDA)-approved biomarker indications to guide targeted therapy options. More recently, it has been appreciated that ctDNA fragmentation patterns are influenced by the chromatin structure of the cell of origin, with greater diversity in fragment size in areas with open chromatin and less diversity in fragment size in areas with closed chromatin. In consequence, multiple studies have found that ctDNA fragmentation patterns can be used to accurately infer epigenomic and transcriptomic phenotypes from their tumor cells of origin. However, these analyses have previously relied on whole-genome sequencing (WGS), and it is not feasible to identify FDA-approved biomarker indications in a cost-effective manner with WGS. Methods: Peripheral blood was collected from a cohort of 90 patients with metastatic HER2-negative breast cancer (ER-positive n=71, ER-negative n=19). Cell-free DNA was extracted from plasma and sequenced using a custom 822 gene pan-cancer targeted sequencing panel (IDT). Shannon entropy of first coding exon fragment sizes (E1SE) was used to quantify fragmentation patterns. Higher diversity of fragment sizes, leading to a higher E1SE, are expected in ctDNA derived from areas of the genome with more open chromatin. A machine learning model utilizing the E1SE metric across all genes in the targeted panel was developed to distinguish between ER-positive and ER-negative disease. Results: Training cross-validated accuracy of the machine learning model was 87.8% with AUC of 0.91 to distinguish between ER-positive and ER-negative disease, despite a median ctDNA fraction of only 0.02. E1SE metrics for ESR1 and CCND1 were significantly higher in ER-positive than ER-negative samples, while E1SE metrics for EGFR, c-Kit and members of the MAP kinase family were significantly higher in ER-negative than ER-positive samples, consistent with anticipated differences in gene expression between ER-positive and ER-negative triple negative breast cancers. In contrast, HER2 E1SE was similar between groups, as expected in this clinically HER2-negative cohort. Conclusions: We have shown for the first time that sequencing from standard targeted ctDNA panels can be utilized to infer phenotypic information through analysis of ctDNA fragmentation patterns in patients with metastatic breast cancer. This expands the depth of potential biologic data that can be extracted from targeted ctDNA sequencing panels in addition to DNA mutation status in a cost-effective manner. In the future, this approach can be exploited to expand ctDNA-based biomarker development beyond DNA mutation status. Citation Format: Kyle Helzer, Jamie Sperger, Yue Shi, Viridiana Carreno, Hannah Krause, Katherine Kaufmann, Leilani Mora-Rodriguez, Matthew Bootsma, Mark Burkard, Ruth O'Regan, Kari Wisinski, Joshua Lang, Shuang (George) Zhao, Malinda West, Marina Sharifi. Fragmentomic analysis of a circulating tumor DNA targeted cancer gene panel discriminates ER status in metastatic breast cancer liquid biopsies [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 PS06-09.

Abstract PO5-17-04: Tolerability of pertuzumab in older adults with HER2 positive breast cancer: A single institution experience

Abstract Background: Tumor HER2 over-expression occurs in 10 to 15% of older adults with breast cancer (BC). Combination HER2-directed therapy (pertuzumab and trastuzumab) with chemotherapy (CT) is the standard treatment for early and advanced HER2-positive bc. However, a study of more than 1,300 Medicare beneficiaries showed that about half of patients (pts) aged 65 or older with stage I to III HER2 positive bc did not receive trastuzumab-based therapy. This is likely due to concern for tolerability as older women remain underrepresented in clinical trials of breast cancer making it difficult to extrapolate tolerability of these agents in these patients. In the Neosphere and TRYPHAENA studies, the mean age of pts were 49.8 and 50.6 years, respectively. We examined the real-world tolerability of pertuzumab in combination with trastuzumab and systemic ct in women over the age of 65 with HER2 positive bc. Methods: An IRB approved retrospective review of medical records was conducted evaluating pts over the age of 65 with early or advanced HER2 positive bc treated at The Ohio State University Comprehensive Cancer center from January 1, 2015 to May,1 2020. Descriptive statistics (means, standard deviations, medians and ranges for continuous variables and frequencies and percents for categorical variables) were used to summarize disease and patient characteristics for pts enrolled in this study and treated with pertuzumab. The total number of planned and completed cycles of treatment as well as the number of treatment delays and dose reductions were also summarized using frequencies and percentages. The same descriptive statistics were used to summarize the number of grade II or IV toxicities and pathologic complete response (pCR) in the neoadjuvant setting. Results: A total of 71 pts met inclusion criteria. Mean age was 76 years (SD 4.1). Of these pts, 62 had stage I-III disease and 9 had metastatic disease. Additionally, 68% (48/71) had estrogen positive (ER) disease whereas 32% (23/71) had ER negative disease. Neoadjuvant systemic therapy was provided to 81% (50/62) of non-metastatic pts and 19% (12/62) received adjuvant therapy. The median number of completed neoadjuvant cycles (ct plus trastuzumab and pertuzumab) was 5.4 (SD 1.5). Among those who received pertuzumab with systemic ct in the neoadjuvant setting, 46% (23/50) of pts achieved a pCR (56% for ER negative disease and 41% for ER positive disease) The median number of completed adjuvant cycles (ct plus trastuzumab and pertuzumab) was 4.9 (SD 2.0). Pts with stage I to III disease completed a mean of 8.6 (SD 5.0) targeted therapy cycles (pertuzumab/trastuzumab). Pts with metastatic disease had a median of 5.7 (SD 1.0) cycles of ct plus trastuzumab and pertuzumab and received a mean of 34.4 (SD 36.0) cycles of maintenance pertuzumab. Treatment delay by 7 or more days occurred in 11% (8/71) of pts whereas 25% (18/71) of pts discontinued pertuzumab early. Pertuzumab termination occurred due to toxicity in 44% (8/18), metastasis in 11% (2/18), and other causes in 44% (8/18) of cases. For toxicities, 2% (1/51) of patients reported grade 3 pain, 25% (2/8) reported grade 3 fatigue, and 12% reported grade 4 diarrhea (1/8) (Table 1). Conclusions: Our study showed that pertuzumab was well tolerated in older pts with bc in the real-world setting. However, 25 % of pts still discontinued pertuzumab early which illustrates the importance of identifying pts who are at higher risk for toxicities prior to starting treatment. Table 1 Reported adverse events in patients age 65 and older receiving pertuzumab Citation Format: Nicole Williams, Austin Warmbier, Dureti Doto, Marilly Palettas, Julie Stephens, Dionisia Quiroga, Kai Johnson, Ashley Pariser, Mathew Cherian, Sagar Sardesai, Daniel Stover, Margaret Gatti-Mays, Robert Wesolowski, Bhuvana Ramaswamy. Tolerability of pertuzumab in older adults with HER2 positive breast cancer: A single institution 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 PO5-17-04.

Abstract PO5-16-02: Investigating survivin as a novel target for immunotherapy in diverse breast cancer patients

Abstract Background: The BIRC5 gene encodes survivin, a tumor-specific antigen associated with aggressive tumor features, Black race and poor prognosis in breast cancer (BC). Recent studies have shown that anti-survivin vaccines stimulate a strong anti-tumor immune response in multiple tumor types. However, the relationship between BIRC5/survivin and immune response in BC is poorly understood, particularly among diverse patients. In this analysis, we sought to investigate the relationship between BIRC5/survivin and the BC immune microenvironment across clinical tumor features and RNA-based risk scores for genomic instability. Methods: We leveraged the Carolina Breast Cancer Study (CBCS), a large population-based study that oversampled young (≤50 years) and Black women with invasive BC. NanoString mRNA expression profiling was used to evaluate breast tumor expression for 10 major immune cell types, adaptive and innate immune response, TP53 and homologous recombination deficiency (HRD) pathways, and BIRC5/survivin from 1952 BC patients, including 1,030 (53%) Black and 922 (47%) non-Black women from the CBCS, with additional comparison in The Cancer genome Atlas (TCGA) (n=1,095 breast tumors). BIRC5 was evaluated both as a continuous and categorical variable, using the third expression quartile as a cut point for BIRC5-high, with the lower three quartiles categorized as BIRC5-low. We used generalized linear models to estimate beta values and adjusted p-values as the measure of association between BIRC5 status and immune-related expression in strata defined by estrogen receptor (ER) status, tumor stage, TP53 and HRD status. All analyses were adjusted for multiple comparisons with the Benjamini-Hochberg procedure. Results: In an analysis of continuous BIRC5 expression and global classes of immune response, BIRC5 mRNA expression was highest among tumors with an adaptive-enriched immune class (p&amp;lt; 0.001) in both CBCS and TCGA. However, when investigating immune gene expression according to BIRC5 status (i.e., BIRC5-high relative to BIRC5-low), multivariate differential expression analysis revealed significantly decreased immune cell-related expression scores among BIRC5-high tumors relative to BIRC5-low, and this relationship persisted in analysis stratified on stage (I/II vs III/IV), ER status, TP53 and HRD status. Across all strata, the strongest relationship between BIRC5-high and the immune microenvironment was observed for adaptive immune response (Beta: -0.14; p=0.005), with decreased immune gene expression related to B cells (Beta: -0.16; p=0.01), T cells (Beta: -0.14; p=0.007), Cytotoxic cells (Beta: -0.14; p=0.005), and PD-L1 (Beta: -0.15; p=0.005), relative to BIRC5-low. Conclusion: High BIRC5/survivin expression is associated with decreased immune-related gene expression in both ER-positive and ER-negative disease, and across all tumor stages. Anti-survivin therapies may be beneficial for boosting immune response in breast tumors with low immunogenicity, offering promise for BC subtypes previously ineligible for immunotherapy. Citation Format: Alina Hamilton, Qichen Wang, Sarah Soppe, Melissa Troester, Yara Abdou. Investigating survivin as a novel target for immunotherapy in diverse breast cancer patients [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-16-02.

Abstract LB009: Unveiling the significance of DARPP-32 and its partners, including GRB7 and DKK1, in breast cancer: Integrative insights from patient data and cell line transcriptomics

Abstract DARPP-32 plays a crucial role in regulating both protein-phosphatase-1 (PP-1) and protein kinase A (PKA), its function being reliant on its phosphorylation status. We have previously demonstrated that low DARPP-32 expression is associated with adverse survival of breast cancer patients, particularly those with oestrogen receptor (ER) positive disease; however, there is limited information on how DARPP-32 may alter breast cancer cell behaviour. We have recently published an integrative approach using patient data and cell line transcriptomics to understand the role of DARPP-32 in breast cancer. We analysed the transcriptome of T47D ER positive breast cancer cells following DARPP-32 knockdown, including treatments in combination with 17β-estradiol or PKA inhibitor fragment (6-22) amide. 202 differentially expressed transcripts were identified in DARPP-32 knock down cells and treatment of these cells with 17β-estradiol or PKA inhibitor fragment (6-22) amide led to the differential expression of 193 and 181 transcripts respectively. Differentially expressed transcripts were compared with genes identified as associated with DARPP-32 expression in 1980 breast cancer patients within the METABRIC cohort using an Artificial Neural Network approach (ANN). Several genes overlapped with those identified from cell line transcriptomics, including PTK7, TRAF5, and KLK6. Both DKK1 and GRB7 were identified as genes associated with DARPP-32 expression in patients using ANN, therefore protein expression was determined in a large cohort of early-stage breast cancer patients (n&amp;gt;1000). We demonstrated that DKK1 and GRB7 protein expression was significantly correlated with DARPP-32 Threonine-34 phosphorylation levels within the same samples (all P&amp;lt;0.05). We have now applied an ANN-based integrative data mining approach to identify genes with the largest effect on other genes resulting in an interactome map, which was based on genes identified within the cell line transcriptomics and original ANN. 1878 genes were identified for inclusion within an interactome map in the total patient cohort, whereas 1003 were identified in ER negative disease alone and 2144 in ER positive disease alone. Pathway enrichment analysis identified the ubiquitin proteosome pathway, the insulin pathway-protein kinase B signalling cascade and the RAS pathway. This study underscores the significance of DARPP-32, a central molecular switch, in breast cancer, elucidating its impact on patient prognosis and highlighting potential molecular targets for therapeutic intervention. The integrative approach combining patient data with cell line transcriptomics provides insights into the complex mechanisms underlying breast cancer progression and opens avenues for further research and targeted interventions. Citation Format: Behnaz Saidy, Richa Vasan, Megan-Rose Greener, Rosie Durrant, Adelynn Immanuel, Andrew Green, Emad Rakha, Ian Ellis, Graham Ball, Stewart Martin, Sarah J. Storr. Unveiling the significance of DARPP-32 and its partners, including GRB7 and DKK1, in breast cancer: Integrative insights from patient data and cell line transcriptomics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB009.

Effect of capecitabine as monotherapy for HER2 normal metastatic breast cancer

This study aimed to evaluate the efficacy of capecitabine monotherapy for patients with human epidermal growth factor receptor-2 (HER2) normal metastatic breast cancer (MBC). The primary endpoint was progression-free survival (PFS), and secondary endpoints included overall survival (OS) and PFS according to treatment line and estrogen receptor (ER) status. Patients who received capecitabine as monotherapy for HER2 normal MBC from 2010 to 2020 were included in this retrospective study. ER status, treatment line, number of treatments, and dates of progression and death were registered. PFS was defined from capecitabine initiation to progression or any cause of death, and OS until any cause of death. Among 162 patients receiving capecitabine, approx. 70% had ER-positive disease. They received a median of six cycles of capecitabine (range 2–45). The median PFS was 4.3 months, with no significant difference between treatment lines. When analyzing PFS according to ER status, a statistically significant difference was observed between those with ER-positive and ER-negative disease, with a median PFS of 5,3 months versus 2,5 months, respectively (p = 0.006). A similar trend was seen for overall survival, with a median OS of 14 months for all patients and 17.8 months versus 7.6 months for patients with ER-positive and ER-negative disease, respectively (p ≤ 0.0001). Patients with HER2 normal MBC receiving monotherapy capecitabine had a median PFS of 4.3 months, and a median OS of 14 months. PFS was consistent regardless of treatment line but differed significantly according to ER status.

Abstract 3464: Development and prospective validation of an estrogen receptor positive breast cancer risk model to identify women who could benefit for risk-reducing therapies

Abstract Background: Breast cancer risk-reducing therapies such as tamoxifen and aromatase inhibitors are effective for ER-positive (ER+) but not for ER-negative disease. As these therapies have side effects it is important to identify women at risk of ER+ disease. We developed and validated ER-specific risk prediction models in a prospective cohort and evaluated the expected gains of predicting ER+ vs overall disease. Methods: The iCARE-Lit model integrates established questionnaire-based risk factors and a 313 variant polygenic risk score. We reparametrized the iCARE-Lit model to estimate risk of ER+ and ER- disease separately by obtaining relative risks from published literature for ages at menarche, menopause, first childbirth, and parity to account for their heterogeneous associations with risk of ER-defined subtypes. We estimated 5-year (yr) absolute risk (AR) for ER+ disease using an overall and ER+ model. We evaluated model performance in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial prospective cohort. This included evaluation of calibration (expected-to-observed (E/O) ratio) and discrimination (area under the receiver operating characteristic curve (AUC)), among 46,571 self-reported non-Hispanic White women aged 50-75 yrs (1,052 ER+ cases with 5 yrs of follow-up from enrollment). We compared projected risk stratification of the overall and ER+ models among eligible US women in terms of proportions of women and future ER+ cases identified above the 3% 5-yr AR threshold recommended for risk-reducing interventions in the US. Results: In predicting ER+ disease in PLCO, on average the overall and ER+ AR were well calibrated; however, models overpredicted risk at the ≥3% 5-yr AR threshold, (E/O = 1.31 (1.20, 1. 42) and 1.23 (1.13, 1.34), respectively. Risk discrimination was similar from the overall and ER+ models (AUC=0.65 (0.64-0.67) and 0.66 (0.64-0.67), respectively. The overall model projected that 16% of women in the US could be eligible for risk-reducing therapies, compared to 11% when using ER+ model, resulting in ~1.4 million less women crossing the risk threshold when using the ER+ score. However, the percentage of ER+ cases in the US population projected to occur within 5-yrs among eligible women was larger for the overall (38%) than ER+ (32%) risk score. Conclusion: Findings suggest that ER-specific risk scores might not offer a substantial advantage compared to overall risk scores to identify women eligible for risk-reducing therapies. Further risk-benefit analyses are needed to quantify the potential gains of predicting ER+ vs overall breast cancer. Citation Format: Thomas U. Ahearn, Srijon Mukhopadhyay, Jeya Balasubramanian, Nilanjan Chatterjee, Montserrat García-Closas, Parichoy Pal Choudhury. Development and prospective validation of an estrogen receptor positive breast cancer risk model to identify women who could benefit for risk-reducing therapies [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 3464.

Abstract IA18: Genetic susceptibility to breast cancer: Recent advances and application to personalised prevention

Abstract The past two decades have seen dramatic progress in our understanding of the inherited basis of breast cancer, driven by large international collaborative epidemiological studies. Genetic factors identified include rare coding variants in susceptibility genes, and more than 200 common polymorphisms, identified through genome-wide association studies (GWAS) and largely in non-coding regions, that confer more moderate risks. The majority of the common variants are more strongly associated with ER-positive disease, but a subset is specifically associated with ER-negative disease. Variants are strongly enriched for regulatory regions and transcription factor binding sites, and the putative target genes are strongly enriched for known breast cancer drivers: however, the underlying target genes and mechanisms remain largely obscure. The associations for common variants appear to be largely independent of each other and can be summarised by a polygenic risk score (PRS) that is strongly predictive of risk. The most extensively validated PRS, comprising 313 SNPs, is associated with a relative risk of approximately 1.6 per standard deviation; women in the top 1% of the risk distribution have an approximately 4-fold risk of ER-positive disease and 3-fold risk of ER-negative disease. The PRS was developed in women of European ancestry but is also predictive of risk in Asian ancestry women, though less so in African ancestry women. In contrast, despite their widespread use, the evidence for association with cancer for coding variants in genes on genetic testing panels is often weak. Recent very large-scale targeted sequencing studies, however, have clarified the position, providing strong evidence for an association between protein truncating or missense variants and breast cancer risk for nine genes: BRCA1, BRCA2, ATM, CHEK2, PALB2, BARD1, RAD51C, RAD51D and TP53. Recent large-scale exome-wide sequencing analysis has shown that rare variants in several additional genes are also risk associated, with the majority being tumour suppressor genes: these include MAP3K1, ATRIP and SAMHD1. These analyses also demonstrate, however, that the contribution of coding variation, beyond the known genes, is likely to be small. The currently identified variants explain about half of the familial risk of breast cancer. Part of the “missing” heritability is due to weaker common variants, many of which should be identified in ongoing larger GWAS. The causes of the remainder are obscure and may include rare non-coding variants, repeat polymorphisms, and epistatic interactions. Risk discrimination is most powerful when all risk factors are considered. The BOADICEA model, implemented in the CanRisk tool, provides a well validated model that incorporates the effects of gene variants, polygenic risk scores, lifestyle factors and breast density to predict breast and ovarian cancer risk. Multiple translational studies are ongoing to evaluate the feasibility and utility of such personalised risk prediction for stratifying screening and prevention. Citation Format: Douglas F Easton. Genetic susceptibility to breast cancer: Recent advances and application to personalised prevention [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr IA18.

Novel breast cancer susceptibility loci under linkage peaks identified in African ancestry consortia.

Expansion of genome-wide association studies across population groups is needed to improve our understanding of shared and unique genetic contributions to breast cancer. We performed association and replication studies guided by a priori linkage findings from African ancestry (AA) relative pairs. We performed fixed-effect inverse-variance weighted meta-analysis under three significant AA breast cancer linkage peaks (3q26-27, 12q22-23, and 16q21-22) in 9241 AA cases and 10 193 AA controls. We examined associations with overall breast cancer as well as estrogen receptor (ER)-positive and negative subtypes (193,132 SNPs). We replicated associations in the African-ancestry Breast Cancer Genetic Consortium (AABCG). In AA women, we identified two associations on chr12q for overall breast cancer (rs1420647, OR = 1.15, p = 2.50×10-6; rs12322371, OR = 1.14, p = 3.15×10-6), and one for ER-negative breast cancer (rs77006600, OR = 1.67, p = 3.51×10-6). On chr3, we identified two associations with ER-negative disease (rs184090918, OR = 3.70, p = 1.23×10-5; rs76959804, OR = 3.57, p = 1.77×10-5) and on chr16q we identified an association with ER-negative disease (rs34147411, OR = 1.62, p = 8.82×10-6). In the replication study, the chr3 associations were significant and effect sizes were larger (rs184090918, OR: 6.66, 95% CI: 1.43, 31.01; rs76959804, OR: 5.24, 95% CI: 1.70, 16.16). The two chr3 SNPs are upstream to open chromatin ENSR00000710716, a regulatory feature that is actively regulated in mammary tissues, providing evidence that variants in this chr3 region may have a regulatory role in our target organ. Our study provides support for breast cancer variant discovery using prioritization based on linkage evidence.

An updated PREDICT breast cancer prognostic model including the benefits and harms of radiotherapy

PREDICT Breast (www.breast .predict.nhs.uk) is a prognostication tool for early invasive breast cancer. The current version was based on cases diagnosed in 1999–2003 and did not incorporate the benefits of radiotherapy or the harms associated with therapy. Since then, there has been a substantial improvement in the outcomes for breast cancer cases. The aim of this study was to update PREDICT Breast to ensure that the underlying model is appropriate for contemporary patients. Data from the England National Cancer Registration and Advisory Service for invasive breast cancer cases diagnosed 2000–17 were used for model development and validation. Model development was based on 35,474 cases diagnosed and registered by the Eastern Cancer Registry. A Cox model was used to estimate the prognostic effects of the year of diagnosis, age at diagnosis, tumour size, tumour grade and number of positive nodes. Separate models were developed for ER-positive and ER-negative disease. Data on 32,408 cases from the West Midlands Cancer Registry and 100,551 cases from other cancer registries were used for validation. The new model was well-calibrated; predicted breast cancer deaths at 5-, 10- and 15-year were within 10 per cent of the observed validation data. Discrimination was also good: The AUC for 15-year breast cancer survival was 0.809 in the West Midlands data set and 0.846 in the data set for the other registries. The new PREDICT Breast model outperformed the current model and will be implemented in the online tool which should lead to more accurate absolute treatment benefit predictions for individual patients.

Endocrine therapy initiation among women diagnosed with ductal carcinoma in situ breast cancer from 2001-2016.

487 Background: Endocrine therapy (ET) initiation in people within 1 year of diagnosis of estrogen-receptor-positive (ER+) ductal carcinoma in situ (DCIS) has ranged from 21-45% in prior studies; however, these studies did not evaluate initiation post-2011 and may not reflect current patterns of use. ET use following ER+ DCIS diagnosis can reduce the relative risks of recurrence and contralateral breast cancer by 30-50%. We evaluated ET initiation over time and by demographic, tumor, and treatment characteristics in the Kaiser Permanente Breast Cancer Survivors Study between 2001-2016. Methods: We included people aged 20+ years diagnosed with unilateral DCIS with at least 1 year of cancer-free follow-up from three U.S. integrated health systems. We excluded people with ER-negative disease, no surgery, and those who received chemotherapy or unknown radiation therapy. ET dispensings (tamoxifen and aromatase inhibitors) were extracted from electronic pharmacy records within 1 year of a person’s initial DCIS breast cancer diagnosis. Using generalized linear models with a log link and Poisson distribution, we estimated relative rates (RRs) of ET use (vs none) over time and by demographic, tumor, and other treatment characteristics. Results: Among 1,782 pre- and postmenopausal people, 577 (32%) initiated ET within 1 year of diagnosis. From 2001-2016, ET use did not change over time (34% vs 36%), tamoxifen use declined slightly (34% vs 29%), and aromatase inhibitor use increased slightly (0% vs 7%). People were less likely to initiate ET if they were ≥65 years, Black, had borderline or unknown ER status, were not tested for ER, had breast conserving surgery (BCS) without radiation, or had a unilateral mastectomy. Conclusions: Only one-third of people with DCIS diagnosed in a community healthcare setting and potentially eligible for ET, initiated treatment within 1 year of their diagnosis. Previous studies have shown long-term benefits of ET use in people with DCIS; however, we saw no increase in use over time. Concerns about side-effects, overdiagnosis and overtreatment of DCIS, and confusion about treatment guidelines may explain relatively low ET initiation.[Table: see text]

Breast Cancer in Pregnant Young Women: Clinicopathological Profile, Survival, and Pregnancy Outcomes.

Background Breast cancer is one of the most common cancer types diagnosed during pregnancy; the presence of any neoplasm in pregnant women faces clinical dilemmas and challenges in cancer and pregnancy management. Pregnancy-associated breast cancer (PABC)is defined as breast cancer diagnosed during pregnancy or within one year after delivery. The aim of this study was to describe tumor clinicopathological characteristics and pregnancy outcomes in PABC patients. Materials and methods This is a retrospective cohort assessing PABC patients. Qualitative variables were compared using Fisher's exact test. Kaplan-Meier method was used to calculate survival. Cox regression and logistic regression methods were used to estimate the hazard ratio (HR) and odds ratio (OR), respectively. Results We assessed 16 PABC patients. Women ≤ 35 years of age were mainly diagnosed at advanced stage (88.8%) with ER-negative disease (77.8%). Patients with >4 pathological lymph nodes (25%; p = 0.001) and ER-negative disease (50%; p = 0.646) showed poor five-year overall survival (OS). In the multivariate analysis, nodal involvement was the main predictor associated with poorer OS (HR = 1.4, 90% confidence interval [CI]: 1.14 to 1.8). The following risk factors might influence the risk of preterm delivery: maternal older age, gestational age at diagnosis, and intrauterine exposure to chemotherapy, but an adjusted OR of 0.61 (90% CI: 0.34 to 1), 0.80 (90% CI: 0.66 to 0.9), and 0.013 (90% CI: 0.00 to 0.9), respectively, did not statistically support such an effect. Conclusions Younger women with PABC had a more aggressive pathological profile that might partly explain the poor OS. Obstetrical adverse events related to preterm delivery should be avoided with better planning of specialized strategies.

Prediction of negative axillary node clearance by sentinel node-positive to total node ratio: a retrospective cohort study.

Increasing evidence suggests that de-escalation of axillary surgery is safe, without significantly impacting patient outcome. Obtaining positive lymph nodes at a sentinel lymph node biopsy (SNB) can guide decisions toward the requirement of axillary nodal clearance (ANC). However, methods to predict how many further nodes will be positive are not available. This study investigates the feasibility of predicting the likelihood of a negative ANC based on the ratio between positive nodes and the total number of lymph nodes excised at SNB. Retrospective data from January 2017 to March 2022 was collected from electronic medical records. Patients with oestrogen receptor (ER) positive and HER2 negative receptor disease were included in the study. ER-negative and HER2-positive disease was excluded, alongside patients who had chemotherapy before ANC. Of 102 patients, 58.8% (n=60) had no macrometastasis at ANC. On average, 2.76 lymph nodes were removed at SNB. A higher SNB ratio of positive to total nodes [OR 11.09 (CI 95% 2.33-52.72), P=0.002] had a significant association with positive nodes during ANC. SNB ratio less than or equal to 0.33 (1/3) had a specificity of 79.2% in identifying cases that later had a negative completion ANC, with a 95.8% specificity of no further upgrade of nodal staging. A low SNB ratio of less than 0.33 (1/3) has a high specificity in excluding the upgradation of nodal staging on completion of ANC, with a false-negative rate of less than 5%. This may be used to identify patients with a low risk of axillary metastasis, who can avoid ANC.

No evidence for a genetic causal effect of breast cancer on venous thromboembolism: a mendelian randomization study.

Active cancer is known to contribute to venous thromboembolism (VTE), but the cause-and-effect association of breast cancer on VTE is not yet clear. In order to investigate the possible causal relationships, we used a Mendelian randomization analysis. Data for generically predicted breast cancer were identified based on the BCAC consortium. A meta-analysis of genome-wide association study (GWAS) comprising 1,500,861 participants for VTE as well as data from the FinnGen study for VTE, DVT and PE was used for the causal-effect estimation. Our primary method was inverse-variance weighted (IVW), and our supplementary methods included weighted median and MR-Egger. We also carried out sensitivity analysis for the study. No evidence of causal-effect was detected of overall breast cancer on VTE in both the GWAS meta-analysis (OR=1.01, 95%CI:0.98-1.04, p = 0.495) and the FinnGen consortium (OR=1.00,95%CI:0.96-1.04, p = 0.945). In addition, the presence of ER-positive or ER-negative disease did not significantly influence the incidence of VTE and its subtypes. In conclusion, no genetic cause-and-effect of breast cancer on VTE risk was detected in the large MR analysis.

Real-world survival of Danish patients with HER2-positive metastatic breast cancer

Background The purpose was to investigate the treatment flow of patients with HER2-positive metastatic breast cancer (mBC), progression-free survival (PFS) and overall survival (OS) across treatment lines and adherence to guidelines (defined as trastuzumab, pertuzumab and chemotherapy first line, where 85% received vinorelbine as backbone and T-DM1 second line). Furthermore, we identified clinical markers to predict the risk of developing brain metastases. Material and Methods Patients with HER2-positive mBC, diagnosed between 01.01.2014–31.12.2019, registered in the database of the Danish Breast Cancer Group were included in this real-word study. Clinical follow-up was assessed until 01.10.2020 and complete follow-up for overall survival until 01.10.2021. Survival data were analyzed using the Kaplan-Meier method with guidelines adherence analyzed as a time-varying covariate, and the risk of CNS metastasis was estimated by the cumulative incidence function. Results 631 patients were included. 329 (52%) patients followed the guidelines. The median OS for all patients was 42.3 months (95% Cl, 38.2–48.4), and significantly higher for the patients who followed guidelines; NA (95% CI, 78.2–NA). The median PFS for all patients was 13.4 months (95% Cl, 12.1–14.8), 6.6 (95% Cl, 5.8–7.6) and 5.8 (95% Cl, 4.9–6.9) for first, second and third line of treatment, respectively. Patients with ER-negative mBC had a higher risk of developing brain metastases and patients with high tumor burden had a higher risk of developing brain metastases with an adjusted HR of 0.69 (95% CI, 0.49–0.98), p = 0.047 and 2.69 (95% CI, 1.45–5.00), p = 0.002, respectively. Conclusion We found that only half of the patients with HER2-positive mBC, received first and second-line treatment according to national guidelines. Patients receiving treatment according to guidelines had a significantly higher median OS compared to patients who did not. We also found that patients with ER-negative disease or high tumor burden had a significantly higher risk of developing brain metastases.

Intra-patient and inter-metastasis heterogeneity of HER2-low status in metastatic breast cancer

IntroductionAnti-HER2 antibody-drug conjugates (ADCs) have shown important efficacy in HER2-low metastatic breast cancer (mBC). Criteria for receiving ADCs are based on a single assay on the primary tumour or a small metastatic biopsy. We assessed the intra-patient inter-metastasis heterogeneity of HER2-low status in HER2-negative mBC. Patients and MethodsWe included samples of 10 patients (7 ER-positive and 3 ER-negative) donated in the context of our post-mortem tissue donation program UPTIDER. Excisional post-mortem biopsies of 257 metastases and 8 breast tumours underwent central HER2 immunohistochemistry (IHC), alongside 41 pre-mortem primary or metastatic samples. They were classified as HER2-zero, HER2-low (HER2-1+ or HER2-2+, in situ hybridisation [ISH] negative) or HER2-positive (HER2-3+ or HER2-2+, ISH-positive) following ASCO/CAP guidelines 2018. HER2-zero was further subdivided into HER2-undetected (no staining) and HER2-ultralow (faint staining in ≤10% of tumour cells). ResultsMedian post-mortem interval was 2.5 h. In 8/10 patients, HER2-low and HER2-zero metastases co-existed, with the proportion of HER2-low lesions ranging from 5% to 89%. A total of 32% of metastases currently classified as HER2-zero were HER2-ultralow. Intra-organ inter-metastasis heterogeneity of HER2-scores was observed in the liver in 3/6 patients. Patients with primary ER-positive disease had a higher proportion of HER2-low metastases as compared to ER-negative disease (46% versus 8%, respectively). At the metastasis level, higher percentages of ER-expressing cells were observed in HER2-low or -ultralow as compared to HER2-undetected metastases. ConclusionsImportant intra-patient inter-metastasis heterogeneity of HER2-low status exists. This questions the validity of HER2-low in its current form as a theranostic marker.

Stressful Life Events, Social Support, and Incident Breast Cancer by Estrogen Receptor Status.

Epidemiologic studies on the association between psychosocial stress and breast cancer risk remain inconsistent, while investigation of whether the association differs by ER status is limited. In this prospective cohort of postmenopausal women, high experiences of stressful life events were positively associated with ER-negative disease but not ER-positive.