Publications by authors named "Kirkner G"

Background: The approval of trastuzumab deruxtecan has prompted the subgrouping of human epidermal growth factor receptor 2-negative (HER2-) breast cancers (BCs) to HER2 0 and HER2 low on the basis of immunohistochemistry, although the biological significance of these subgroups remains uncertain. This study is aimed to better understand the molecular and genetic differences among HER2- tumors stratified by quantitative levels of HER2.

Patients And Methods: We analyzed the transcriptomic and genomic data from the Molecular Taxonomy of BC International Consortium (discovery cohort) and The Cancer Genome Atlas (independent validation cohort).

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Background: Compared to older adults with breast cancer (BC), adolescents and young adults (AYAs) develop more aggressive disease necessitating more intensive therapy with curative intent, which is disruptive to planned life trajectories. The burden of unmet needs among AYA BC survivors exists in two domains: (1) symptoms (e.g.

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  • Many young women diagnosed with breast cancer (BC) are interested in breastfeeding after treatment, but there's limited information on their experiences.
  • In a study of 143 women diagnosed with BC, around 55% attempted breastfeeding, with satisfaction rates high despite challenges such as mastectomies and low milk production.
  • There's a need for more specific resources and support for BC survivors who want to breastfeed, as many women reported receiving helpful information only from their oncology teams or online.*
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Purpose: Triple-negative breast cancer (TNBC) is a heterogeneous disease that carries the poorest prognosis of all breast cancers. Although novel TNBC therapies in development are frequently targeted toward tumors carrying a specific genomic, transcriptomic, or protein biomarker, it is poorly understood how these biomarkers are correlated.

Experimental Design: To better understand the molecular features of TNBC and their correlation with one another, we performed multimodal profiling on a cohort of 95 TNBC.

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  • - The study examined the cardiovascular disease (CVD) risk linked to cancer treatments in young women (≤40 years) with breast cancer, focusing on data from 372 survivors over five years.
  • - Findings revealed that radiation treatment, especially left-sided radiation, was associated with a significant increase in excess heart age, while systemic cancer treatments showed no correlation with heart age changes.
  • - The authors suggest that CVD risk assessment tools should integrate cancer treatment history to better identify young breast cancer survivors at high risk for cardiovascular issues.
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Purpose: Compared with older women diagnosed with breast cancer, younger women are more likely to die of breast cancer and more likely to suffer psychosocially in both the short-term and long term. The Young Women's Breast Cancer Study (YWS) is a multisite prospective cohort study established to address gaps in our knowledge about this vulnerable and understudied population.

Participants: The YWS enrolled 1302 women newly diagnosed with stages 0-IV breast cancer at age 40 years or younger at 13 academic and community sites in North America between 2006 and 2016.

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Purpose: We evaluated the incidence, timing, and risk factors for second primary non-breast cancers (SPNBC) among young breast cancer (BC) survivors.

Methods: This study included participants of the Young Women's BC Study (YWS) who were diagnosed with stage 0-III BC between 2006 and 2016 and age 40 or younger at diagnosis (N = 1,230). Patient characteristics, treatment information, and clinical events were collected via serial surveys.

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The ESR1 ligand binding domain activating mutations are the most prevalent genetic mechanism of acquired endocrine resistance in metastatic hormone receptor-positive breast cancer. These mutations confer endocrine resistance that remains estrogen receptor (ER) dependent. We hypothesized that in the presence of the ER mutations, continued ER blockade with endocrine therapies that target mutant ER is essential for tumor suppression even with chemotherapy treatment.

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  • Inflammatory breast cancer (IBC) is a rare and aggressive form of breast cancer, with limited understanding of its biological mechanisms due to insufficient genomic studies.
  • A study analyzing data from 2457 patients found that IBC cases were generally diagnosed at a younger age and had higher grades, with significant associations to hormone receptor-negative and HER2-positive tumors.
  • The research revealed frequent somatic alterations in IBC, particularly in HER2-positive cases, and highlighted the NOTCH pathway's potential involvement, while overall genomic differences between IBC and non-IBC were minimal, suggesting the complexity of IBC pathology.
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Importance: Among women diagnosed with primary breast cancer (BC) at or younger than age 40 years, prior data suggest that their risk of a second primary BC (SPBC) is higher than that of women who are older when they develop a first primary BC.

Objective: To estimate cumulative incidence and characterize risk factors of SPBC among young patients with BC.

Design, Setting, And Participants: Participants were enrolled in the Young Women's Breast Cancer Study, a prospective study of 1297 women aged 40 years or younger who were diagnosed with stage 0 to III BC from August 2006 to June 2015.

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  • The study explores the effectiveness of next-generation sequencing (NGS) in predicting HER2 status in breast cancer, comparing it to traditional methods like immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH).
  • The analysis involved 294 cases and found a strong correlation between NGS-derived data and HER2 status, with a specific log2 ratio cutoff of 1.7 indicating HER2 positivity with 100% specificity.
  • The findings suggest that NGS-derived copy number data could be a reliable tool for HER2 evaluation in clinical settings.
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  • The study analyzes genomic data from 1,039 patients with HER2-negative metastatic breast cancer to compare HER2-low and HER2-0 tumors.
  • There is a significant difference in ERBB2 allele copy counts, with HER2-low tumors having a median of 2.05 compared to 1.79 in HER2-0 tumors, and HER2-0 tumors showing a higher rate of ERBB2 hemideletions (31.1% vs. 14.5%).
  • Overall, aside from these differences, the genomic characteristics and tumor mutational burden are similar between HER2-low and HER2-0 tumors.
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Background: Breast cancer (BC) is the most common malignancy in women of reproductive age. This study sought to explore the postcancer conception and pregnancy experience of young BC survivors to inform counseling.

Methods: In the Young Women's Breast Cancer Study (NCT01468246), a multicenter, prospective cohort, participants diagnosed at age ≤40 years with stage 0-III BC who reported ≥1 postdiagnosis live birth were sent an investigator-developed survey.

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Purpose: Young women treated for breast cancer with cytotoxic therapies are at risk for clonal hematopoiesis of indeterminate potential (CHIP), a condition in which blood cells carrying a somatic mutation associated with hematologic malignancy comprise at least 4% of the total blood system. CHIP has primarily been studied in older patient cohorts with limited clinical phenotyping.

Experimental Design: We performed targeted sequencing on longitudinal blood samples to characterize the clonal hematopoietic landscape of 878 women treated for breast cancer enrolled in the prospective Young Women's Breast Cancer Study.

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Background: It is unclear whether diabetes and glycemic control affects the outcomes of breast cancer, especially among those with metastatic disease. This study aims to determine the impact of diabetes and hyperglycemia on cancer progression and mortality in individuals with metastatic breast cancer (MBC).

Methods: Patients with a diagnosis of MBC between 2010 and 2021 were identified using the MBC database at 2 academic institutions.

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Purpose: To examine the prevalence and dynamics of circulating tumor DNA (ctDNA) and its association with metastatic recurrence in patients with high-risk early-stage hormone receptor-positive breast cancer (HR+ BC) more than 5 years from diagnosis.

Methods: We enrolled 103 patients with high-risk stage II-III HR+ BC diagnosed more than 5 years prior without clinical evidence of recurrence. We performed whole-exome sequencing (WES) on primary tumor tissue to identify somatic mutations tracked via a personalized, tumor-informed ctDNA test to detect minimal residual disease (MRD).

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Purpose: Young age at breast cancer diagnosis correlates with unfavorable clinicopathologic features and worse outcomes compared with older women. Understanding biological differences between breast tumors in young versus older women may lead to better therapeutic approaches for younger patients.

Experimental Design: We identified 100 patients ≤35 years old at nonmetastatic breast cancer diagnosis who participated in the prospective Young Women's Breast Cancer Study cohort.

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Background: Breast cancer in young women is more likely to have higher risk features and be associated with germline BRCA1/BRCA2 mutations. We present the clinicopathologic features of breast cancers in a prospective cohort of young women, and associations between surrogate molecular subtype and BRCA1/BRCA2 mutation status.

Methods: Histopathological features, biomarker status, tumour stage and BRCA status were collected.

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Background: Early reports suggested increased mortality from COVID-19 in patients with cancer but lacked rigorous comparisons to patients without cancer. We investigated whether a current cancer diagnosis or cancer history is an independent risk factor for death in hospitalized patients with COVID-19.

Patients And Methods: We identified patients with a history of cancer admitted to two large hospitals between March 13, 2020, and May 10, 2020, with laboratory-confirmed COVID-19 and matched them 1:2 to patients without a history of cancer.

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Purpose: Existing cell-free DNA (cfDNA) methods lack the sensitivity needed for detecting minimal residual disease (MRD) following therapy. We developed a test for tracking hundreds of patient-specific mutations to detect MRD with a 1,000-fold lower error rate than conventional sequencing.

Experimental Design: We compared the sensitivity of our approach to digital droplet PCR (ddPCR) in a dilution series, then retrospectively identified two cohorts of patients who had undergone prospective plasma sampling and clinical data collection: 16 patients with ER+/HER2- metastatic breast cancer (MBC) sampled within 6 months following metastatic diagnosis and 142 patients with stage 0 to III breast cancer who received curative-intent treatment with most sampled at surgery and 1 year postoperative.

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Background: Beyond known familial colorectal cancer (CRC) syndromes, the mechanisms underlying the elevated CRC risk associated with CRC family history remain largely unknown. A recent retrospective study suggests familial clustering of CRC with hypomethylation in long interspersed nucleotide element 1 (LINE-1). We tested the hypothesis that CRC family history might confer a higher risk of LINE-1 methylation-low CRC.

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Purpose: More than 20 million archival tissue samples are stored annually in the United States as formalin-fixed, paraffin-embedded (FFPE) blocks, but RNA degradation during fixation and storage has prevented their use for transcriptional profiling. New and highly sensitive assays for whole-transcriptome microarray analysis of FFPE tissues are now available, but resulting data include noise and variability for which previous expression array methods are inadequate.

Experimental Design: We present the two largest whole-genome expression studies from FFPE tissues to date, comprising 1,003 colorectal cancer (CRC) and 168 breast cancer samples, combined with a meta-analysis of 14 new and published FFPE microarray datasets.

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Experimental studies have shown that estrogen- or progesterone-activated signaling leads to growth inhibition effects on colon cancer cells through the upregulation of several cell-cycle regulators. However, epidemiologic studies evaluating hormone therapy use and colorectal cancer risk by the status of cell-cycle regulators are lacking. In this study, we used data from the prospective Nurses' Health Study to evaluate whether the association between hormone therapy use and colorectal cancer risk differs by the molecular pathologic status of microsatellite instability (MSI) and expression of cell-cycle-related tumor biomarkers, including CDKN1A (p21, CIP1), CDKN1B (p27, KIP1), and TP53 (p53) by immunohistochemistry.

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Purpose: Previous studies have examined predictors for initiation of adjuvant chemotherapy in stages II and III colon cancer. However, little is known regarding the use of specific chemotherapy regimens or treatment duration.

Patients And Methods: We studied treatment records for 2,560 patients with stage II or III colon cancer who received adjuvant chemotherapy between January 2004 and April 2010 at US cancer care facilities participating in a nationwide, commercially available chemotherapy order entry system that captures patient demographics, stage, and details of chemotherapy treatment.

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